HYDROPONICS, THE BASICS
The most important thing for you is to
realize is that Hydroponics should be easy. It is easier for the home grower to
grow Hydroponically than in soil and that’s a fact! This is the reason for
this booklet. In this booklet I hope to show you how easy, how inexpensive, and
how satisfying Hydroponics is. Simply there is no easier way to grow, house
plants, ornamental plants, vegetables such as tomatoes, lettuce, beans, fruit,
root crops such as potatoes, carrots, onions, flowers such as roses and
carnations, bulbs, vines, trees, orchids, herbs, anything in Hydroponics. To my
knowledge, there is nothing that is grown that cannot be grown using hydroponic
techniques. In Europe they call
Hydroponics, “soil-less culture”. This is in fact, the best possible way to
describe what we do. We take away the nutritional control of soil, by using a
balanced liquid containing 99.9% water, and 0.1% of the Minerals found in soil.
Instead of soil giving out some nutrient whenever it can, Hydroponics gives the
right amount all the time. Hydroponic nutrient is totally organic (in terms of
not artificial or synthetic compounds), except the minerals are mined from the
ground and are then balanced to exact proportions, so your plant will get
exactly what they need, nothing more, and certainly nothing less! In fact if we
could take the perfect soil and dissolve it, we would have exactly what a
nutrient solution is, totally natural, but under your control.
Apart from nutrients, the most
important thing we do in a Hydroponic growing design is make sure the plants
have access to Oxygen. Basically, this means that they are not growing in water
so they drown, but have a supply of air around their roots. I will explain more
about this shortly.
The burning question in your mind should
be:-
How do I get started in Hydroponics?
This is the question I most want to
answer in this book. I will discuss the major systems and hopefully lead you to
the conclusion that Hydroponics is EASY.
To get started in Hydroponics is as
simple as deciding what system will best suit the plants I wish to grow? This
question determines the type of system.
The systems described further on
explain whether they suit small plants like lettuce and herbs with smaller root
systems or larger plants like tomatoes and cucumbers with larger root systems,
short term crops like lettuce or long term crops that will be in the system for
more than 3-4 months. Remember,
plants such as tomatoes can be harvested and removed, from short-term systems,
before they clog up the system with roots, but some crops will be harvested for
long periods. E.g. flower and cannabis crops may cut without the actual plant being
removed. These can be an extreme example, of a long-term crop, but their roots
could be trimmed, or plants replaced with young seedlings instead of
re-cropping.
We’ll discuss more with each system.
THE FIVE BASICS
1.
LIGHT
Light is the energy that creates life.
Life cannot exist without it, and cannot thrive without enough of it. Plants
process up to 5,000 foot-candles of light intensity to get the energy to grow.
The sun is around 1,000,000 foot-candles. Shade
can be lower than 1,000 foot-candles.
Plants will enjoy much light, but some
do not like all the heat put out by sunlight. Shade cloth is ideal for hot
conditions, also to keep plants from, insects, wind, rain and other damage, but
rarely is the requirement for low light levels.
Sunlight is an ideal source of light
for plants. It is bright and contains the Reds and Blues necessary to produce
good healthy growth. However it also has infrared, Green and Ultra-Violet light.
The infrared light or heat is
absolutely necessary or we would all freeze to death, but it can be too little
or too much heat. Too little heat is best combated by using a recirculating
hydroponic system. By heating the nutrient in the tank, and pumping the 20 to
25C nutrient around we can keep the plants warm.
Excess heat in summer, can be alleviated by cooling the tank, usually by
aerating the tank heavily. By using a venturi, a water jet, or having the
nutrient rising and falling into the tank like a waterfall will cool the
nutrient as it passes through the air.
It is not necessary to worry about
green light as it is usually reflected off the leaves, making them look green.
There is some evidence that shows that a reduction in Ultra Violet (or UV) light
can improve growth. If you are growing under glass or plastic this may interest
you.
We generally grow outdoors, so just
use common sense. If you’d feel hot or cold in the sunlight, then the plants
would feel that too. Plants tend to grow well in the same climate as humans feel
comfortable. A great way to grow is
under artificial horticultural lights that will allow more control, and less
damage from the elements, but that is a decision you can make. What I can tell
you is that, a 400-Watt plant light, costs very little to run, but the benefits
are, faster growth (from up to 18 hours of light per day), more control of the
seasons through day length, less pest problems, no wind, rain and less cold
problems. But you may need an exhaust fan to ensure good air circulation and no
heat build up in warm climates. (See Appendix on Artificial Light)
RULE: A PLANT GETS ALL ITS ENERGY FROM
THE LIGHT IT ABSORBS THROUGH ITS LEAVES. LOWER THE LIGHT LEVELS AND YOU REDUCE
THE GROWTH RATE.
2.
OXYGEN TO NUTRIENT RATIO
Oxygen keeps a plant’s roots healthy
and allows the plant to take up nutrient. Oxygen
is the key to growth rate. Without oxygen around the roots, the roots will rot
and die. You cannot grow in water, unless you dissolve oxygen in it. The
recommendation is that you do not grow in water, just feed enough nutrients to
keep the roots moist, with access to oxygen. The 5 systems I have described in
this book will have varying degrees of oxygen according to their design. The
oxygen level or the oxygen to nutrient ratio is the key to success.
RULE: PLANTS CANNOT TAKE UP THEIR
NUTRIENTS UNLESS OXYGEN IS PRESENT. THE MORE OXYGEN, THE FASTER THE UPTAKE OF
NUTRIENT.
3.
NUTRIENT STRENGTH
Assuming you have a commercial brand
of nutrient made by a good Australian company such as Accent Hydroponics, Growth
Technology or the like, you will get excellent consistency in the nutrient.
Always use a 2 part A&B style nutrient where possible. Nutrients must be
solely designed for Hydroponics. Soil fertilisers require bacteria to break down
more complex elements into useful ones. They are likely to be less soluble, not
pH adjusted, and are usually too slow to release the necessary elements to be
suitable for Hydroponic systems. Plants may grow for a little while in
Hydroponics using soil fertilisers but they generally exhibit minor mineral
deficiencies, then develop major deficiencies, until even changing to a
Hydroponic nutrient can not correct the disorders. Soil fertilisers normally
kill hydroponically grown plants, but not overnight. Certainly they will never
produce as nature intended them to if you do not supply the right amount of
minerals in a soluble form.
There are a range of companies
offering a grow (High Nitrate) nutrient and a bloom (high Potash) nutrient.
Neither will MAKE a plant do anything. You can use these formulas to approximate
the nutritional requirements of your plants. When growing, a plant generally
takes more nitrates, and during flower production and/or fruit production,
plants generally increase their potash and phosphate uptake, but lessen their
need for nitrates. However, in cloudy, overcast or short days of the year, the
plants will take up more potash and phosphorus due to lower light levels, and on
sunny, long, cloudless days the plants nitrate uptake is greater. Sounds
confusing? It isn’t really. Most manufacturers put an excess of everything
into their general-purpose nutrients. But when in doubt, ask a store. Also, when
people tell you an imported nutrient is better, don’t believe them, unless
they’ve tested a good Australian nutrient with a growth additive like
Superthrive, Budwiser or Organic Growth Promotant (OGP). They will find out
smartly, that these nutrients only grow a bit better because of the Americans
and other countries put small amounts of hormones or vitamins into their
nutrients - and imported nutrients cost more! Use Australian nutrients, and to
boost growth, add a good plant hormone and Plant Vitamin treatment to the
nutrient. You will be amazed!
Once you have a good brand of
nutrients, mix exactly to directions. Less is better than too much. Less will
make a plant grow faster, but more stretched, and leafy than normal. More will
create a compact plant that hardly grows upward but is extremely bushy, woody,
but can be a heavy bearing fruiter/flowerer.
If nutrient strength is strong or weak to the extreme, this will lead to
deficiencies or death. E.g., too strong, and calcium is deficient because the
plant is not taking up nutrient fast enough. If the nutrient is too weak, it is
the same deficiency, but due to insufficient calcium in the nutrient. Follow
directions and ask a store what to do. Nutrient strength can be read and
adjusted by electronic conductivity meters.
Ask your store what a conductivity meter will cost. (See also Appendix on
advanced nutrient control through CF adjustment)
RULE: THE NUTRIENT CONTENT AND
STRENGTH GOVERNS HEALTH, HEIGHT, LEAF AND FLOWER PRODUCTION, AND ALL GROWTH
ASPECTS.
4. NUTRIENT pH (ACIDITY AND ALKALINITY)
pH is the level of acidity or
alkalinity of the nutrient solution. Think of it as sweet and sour. Most
nutrients in town water will be within the range of 6 to 6.5 pH. ALL PLANTS GROW
IN THIS RANGE IN HYDROPONICS. Anyone who tells you otherwise, is either
horticulturally trained in soil only or is reading materials drawn from soil
based research and is therefore untrained for plant nutrition in Hydroponics. I
extend my apologies to Horticulturists. Some of you do understand the
nutritional simplicities of Hydroponics, but 4 years of soil training is hard to
overcome, research into Hydroponics is still new, and soil nutrition is not
suitable for the simple Hydroponic plant. If
recycling nutrient, pH and Nutrient strength can change as certain elements are
taken in by the plant. All you have to do is change the nutrient for fresh
nutrient as often as possible, or adjust to the correct reading with a set of
meters. If the nutrient is too sweet or too sour, the plants will develop
deficiencies. I will discuss manual care, electronic adjustment, and computer
control later. As discussed in water purity - pH must be checked if you are
using rain, dam, bore water or any other source than town supply.
RULE: pH IS THE KEY TO KEEPING PLANTS
FEEDING ON THE CORRECT ELEMENTS, AND KEEPS THEM FROM DEFICIENCIES.
5. TEMPERATURE AND FRESH AIR
Optimum temperature depends on the
plants. Generally, Phosphorus up-take is severely impeded below 15 degrees
Celsius, so that’s our bottom temperature. It is recommended to heat the
nutrient if it is below 15 degrees Celsius for more than 4 hours per day.
Maximum temperatures are, (as a guide) around 30 degrees Celsius but as long as
it is well below the temperature where humans start to sweat the plants should
be all right.
Use common sense. If the plants are in
20-25 degree temperatures and 40-60% humidity, then it is likely that you would
feel comfortable where the plants are. By coincidence, plants tend to grow best
in climates approximate to human comfort. So if you visit your plants and it
feels like a blast furnace, or a freezer, it is likely they would benefit from
some attention on the matter. Fresh
air is absolutely essential in shade-house, tunnel-houses, glasshouses and
grow-rooms, as the Carbon Dioxide the plants breathe is essential for every
plant process. Poor ventilation will kill plants, as surely as poison. You will
notice ventilation problems by the better growth near vents, doors, or fans. If
plant growth is more sluggish away from these areas, then you should improve
your fresh air, or use Carbon Dioxide enrichment systems to add CO2.
RULE: PLANTS NEED CARBON DIOXIDE IN
EVERY PLANT PROCESS. THEY NEED FRESH AIR, NOT TOO MUCH HEAT OR THEY CANNOT
PROCESS DUE TO WATER LOSS AND NOT TOO COLD OR THEY CAN’T GET THEIR FOOD.
Plus one other basic:
WATER PURITY
Town water is generally suitable for
Hydroponics, but if you are using bore water, spring water, dam water or rain
water, you may have to check to see if this is suitable.
What problems could occur, is the salt
content of the water, may be too high, the zinc content from metal (zincalume)
tanks, could make it toxic for plants (even though it may be still safe for us
to drink), as well as any number of chemicals, poisons or fertilisers, could be
contaminating the water supply. Please
speak to a Hydroponic Company about the water supply if you are unsure.
In all the above cases, pH control of
nutrients is required.
However town water is generally fine.
Now we have looked at common sense
approaches to growing conditions, we can identify 90% of problems and correct
them. Let’s have a look at the five systems!
SYSTEM ONE:
Perlite
and Vermiculite.
SETUP COSTS LOW.
RUNNING COSTS AVERAGE.
EASY TO BUILD VERY EASY.
EASY TO RUN VERY EASY.
MAINTENANCE FREE AVERAGE.
RESULTS GOOD.
THE INGREDIENTS ARE:
GOOD LIGHT LEVELS.
PERLITE AND VERMICULITE.
WATER WITH HYDROPONIC NUTRIENTS.
CONTAINERS, POTS WITH SAUCERS OR
RESERVOIRS.
Variations could be Polystyrene Boxes,
Planter Bags, Channels, Plastic Tubs, and Buckets.
Concept:
Perlite is a white porous substance
that is Very light and made from volcanic glass. It is an excellent soil
substitute and will hold moisture for short lengths of time. Vermiculite is made
from mineral ore and appears as a brown flake that can hold 100-300 times it's
own weight in water. By adding two parts of Perlite, and one part Vermiculite in
a well draining container, the nutrient solution that will be absorbed and held
by the Perlite and Vermiculite mix is the right amount to keep the roots moist
(a good ratio of oxygen to nutrient). This Mix will enable you to feed a plant
and still keep the roots healthy. Perlite and Vermiculite are both Sterile and
contain no disease or bacteria due to the heating in their manufacture.
Design:
Garden Pots are the easiest containers
to use. By keeping the Perlite and Vermiculite Mix moist, the plants can draw
upon the nutrients and grow. System variations. If using Polystyrene Box or
Plastic container drill a hole in the side about 5 to 10% up from the base of
the box, so that you will have a reservoir of nutrient in the bottom. (e.g., in
a 10-cm high container, make a hole about 0.5 to 1 cm from the bottom.) The
other benefit is that if you over-water, or rain fills the box the hole will
provide drainage. Plastic sheeting inside a wooden frame can make a good garden
bed. Make sure there is a slope on the bed and a point to drain off rain or
over-watering of nutrient. If using PVC pipes or channels filled with the
Perlite and Vermiculite Mix, ensure a slope and drainage point. Remember, in all
designs, look for a system that will drain if saturated.
Set-up:
1. If potting an established plant
first wash roots thoroughly in tepid water to remove soil and place in cannabis or
container. If starting from seed go to step 2.
2. Empty perlite into container (around roots if potting
established plant) and wet with fresh water. If starting from seed, sow seeds so
that the Perlite and Vermiculite mix just covers the seeds and keep the seeds
moist with fresh water.
3. Feed plants with nutrient when seeds have fully germinated
. The seeds should be seedlings after the first seed leaves or cotyledons have
appeared and the first true leaves have opened. This indicates that the
seedlings have developed roots and can now feed on nutrients.
Maintenance:
(or how to keep the plants growing)
All you need to do, is check the
saucer or reservoir, to see if it is dry and see that the Perlite and
Vermiculite is still moist. Ensure that the Perlite is moist; do not worry if
the top is a little dry. Test by pushing your finger down into the mix. The
lower parts where the roots are should be moistened by capillary action from the
bottom saucer or reservoir. The top area may be dryer due to evaporation.
Problems:
If your plant does not look as healthy
as it should, you should flush the Perlite and Vermiculite with half strength
nutrient until it drains freely out the bottom of the cannabis. This will wash any
nutrient inconsistencies out and replace with a good supply of nutrient. If the
plant is not draining freely, then something is wrong; i.e. the plants are water
logged and are drowning. Check drainage holes are not blocked. If problem
persists, please contact your nearest store.
Growth
rate (oxygen : nutrient ratios)
Because Perlite and Vermiculite are
lightweight the oxygen levels are good. Because the nutrient is not recycling,
the dissolved oxygen levels are low. Growth will be better than soil, but less
than recirculating systems.
Heat
and Cold Control:
Generally heating and cooling methods
are not available because this system does not generally recalculate. Placing
pots on a heated bed can work in cold climates.
Suitable
crops:
All
Crops.
Short-term crops only need a small container.
Root crops need depth, Carrots and
Onions about 20 cm. For Potatoes, cover seed Potatoes and water till moist. As
the shoots appear, cover with more Perlite and Vermiculite. The higher the
container the better, (best in a Plastic Garbage bin with drainage holes). Try
and let root crops like Carrots and Onions dry out a little before re-watering.
For example, after a saucer has been empty a day,
then water....
Tall plants and heavy feeding plants
need large pots or containers to draw nutrient from. The Larger the cannabis, the
more Perlite Mix and therefore, the more nutrient held in reserve. Use large
pots if you water infrequently.
Good system for permanent and root
crops.
Great system for houseplants too!
Set-up
Costs:
Enough Perlite and Vermiculite to do
Five 200 mm (8") pots costs around $10-$15 Perlite and Vermiculite breaks
down into a fine powder in 2 to 5 years. However, if the Perlite Mix becomes
contaminated by soil, bacteria or disease, then you should discard and restart.
Pots/Boxes:
Pots or Boxes at cost according to
size and shape. Polystyrene Foam
Boxes are easy to break.
Plastic
lined beds:
Plastic film is usually around $7 for
3m x 1m of black heavy-duty plastic panda film. Replace plastic if torn, but
don't repair as some glues used for patching holes can be really toxic to
plants. Timber Framing costs can be high. Try Bricks or other frames. I
recommend for drainage, pest control and sterility, that you do not line a
channel dug in the ground or use earth walls.
PVC
Channel:
Use ONLY UV stabilised channels or
they will crack in sunlight. Storm-water pipe is designed to be underground,
away from UV light!
Running
Costs:
Nutrients should start at about $7-$8
(about 50 litres of watering solution) and a standard hobby pack at $20 (200 to
400 litres of watering solution) Running costs should be quite low, unless
plants are in hot areas that create evaporation.
Options:
Auto cannabis valves, feed plants automatically. Cost around $22 to
$25. Connect to a drum and the valve will fill a container to 20-30 mm of
nutrient, then wait until dry before filling to 20-30 mm again. Ideal to use for
maintenance free growing by using large drums for reservoirs, especially for
growers that travel away for many days or weeks.
Wick
Systems:
By filling a tube with Perlite, you
create a wick. This Perlite wick can draw nutrients from a bottom tray, up as
much as 10 cm to moisten an upper tray. Many basic kits sold by Hydroponic
stores use this design. If designing a wick system, steal their design first!
Then grow for it. In fact tell the store what you’re doing. They'll probably
help you do it!
Expansion:
Expanding your system is not difficult. Generally you just add
more systems. Perhaps you could connect all trays with hoses, so that any
nutrient in the base of one cannabis can be equally used by pots with more thirsty
plants. If doing so, be careful to check for leaks. If the nutrient leaks away
the plants can just seem unnaturally thirsty!
Variations
of materials used:
DO NOT use metal containers near
hydroponic solution unless a very good layer of plastic has been coated onto it.
Generally, plastic is the best container for all Hydroponics. Some plastics can
be toxic to plants, and some pots are made of this reground plastic, usually
recycled plastic with Lead in it. This type of plastic is not high quality and
is usually black, so if you have cheap and nasty looking containers; try this
test. Put some of the plastic in boiling water. SNIFF THE WATER; if you can
smell the plastic, it probably is toxic. SECOND, TASTE THE WATER when it's
cooled enough. If you can taste plastic, then it's probably toxic. Ask a good
store if in doubt.
Pre-built systems are available in
most stores. Asking for a starter kit usually means a Perlite and Vermiculite
growing system. Check your stores out. Steal their designs if you want but don't
forget to buy some of the ingredients from that store.
This system is good for beginners, and
is the best system for the hobbyist to grow Carrots, Onions, Potatoes, and other
"root" vegetables and bulb crops. It is highly unlikely to cause
problems unless the Perlite mix is saturated and the roots are drowning.
For a basic system, I think it is
ideal for everyone.
SYSTEM TWO:
NFT or Nutrient Film Technique.
SETUP COSTS AVERAGE.
RUNNING COSTS LOW.
EASY TO BUILD SMALL AMOUNT OF SKILLS.
EASY TO RUN VERY EASY.
MAINTENANCE FREE VARIES BETWEEN TWICE
A WEEK AND AUTOMATIC.
RESULTS EXCELLENT.
Ingredients.
The ingredients for NFT are - flat
bottomed channels/gullies.
As an option they would be preferably
in one piece only (not lid and base).
Irrigation lines.
Pump and tap to draw excess pump
pressure away from main feed line.
Plastic or fibreglass tank.
Filter system such as header box.
Stand for channels if necessary.
50 mm pots for seed raising if
starting from seed.
Sterile (& fertiliser free) seed
raising mix (Perlite and Vermiculite Mix).
Nutrients.
Concept.
Dr. Allan Cooper in England invented
this technique, during the 1970’s to save the British Glasshouse industry from
cheaper European imported vegetables. It
had to be inexpensive to produce crops, and inexpensive to set-up. Therefore,
the nutrient should be the only cost for running (except minimal pump power),
and there should be minimal need for cleaning and other labour. NFT has proven
to be one of the top performance systems, as well as being the lowest
maintenance system in terms of cost.
The Concept of NFT is simple. The
plant roots grow on a surface that has no more than 1 mm of nutrient moving
slowly across it. This is called Nutrient Film Technique, as the nutrients are a
film on the base of a flat surface (like a damp surface). The plants roots are
not submerged, and have access to the air, yet can draw up as much nutrient as
they require from the damp surface. We usually use channels for this as channels
or gullies keep the light out of the root zone. Light on the roots generally
slows the growth rate. By having a running Solution of 750 ml to 1 litre per
minute down a flat surface at 1:40 slope (1:40 = 25 mm drop every meter) we can
achieve the nutrient film.
Design.
Remember our basics. We must have good
light levels. Tiered systems can cut down light because of the plants above
shading the lower plants. The standard system is a table of parallel channels
with a fall of 1:40 built into the stand that holds the channels. We must have
good Oxygen levels; therefore we must control the flow rate exactly. We must
control both nutrient strength and nutrient pH, and as this is a recirculating
system, we can optimise the nutrient readings easily by testing and adjusting,
or by dumping and restarting the nutrient. We must have good ventilation,
therefore plants must be spaced for airflow, and the channels should be off the
ground, to provide additional ventilation. The stands also keep soil pathogens
away from the system and a number of pests as well. The Stands make it easier to
plant and harvest plants as there is minimal bending and stretching for the
grower.
We will feed each gully through two
small dripper lines to ensure that each channel receives the same amount of
nutrient. (You will note that we also use two drippers instead of one, so that
in the event of one blocking up, there will still be some flow of nutrient into
the channel). We see in figure 2.1 how the channel has a nutrient film of 1 mm
running down a 1:40 slope, and the plant holes that will take either a seeding
or a small cannabis. These small pots
give the seed the minimum amount of moist seed raising mix to start the seed
off.
The roots of the seedling will quickly
grow out of the bottom of the cannabis, and lift the cannabis to keep the seed raising mix
dryer from this point on. This will eliminate stem rot problems caused by high
moisture and low oxygen within the cannabis.
We see in figure 2.2 how the roots are
exposed to the air in the channels, and kept moist by the roots drawing up the
nutrients by capillary action (like laying a sponge on a damp surface.)
We see in Figure 2.3 a table set-up,
noting stand fall, tank and pump placement (do not use gravity feed as it
complicates the whole idea of simplicity. Besides,
a small 10 Watt Submersible pump only costs about Aust $8.75 per year to run
flat out)
We see in Figure 2.4 the irrigation
lines. Note the use of 15 mm PVC pressure pipe to balance the pressure to each
dripper and the optional unscrewing end cap to flush the pressure line in the
event of contaminants or grime that might block drippers. The drippers are 4 mm
micro-tube and are placed into the pressure line by drilling a hole that is
slightly smaller (usually 7/32nd drill bit) and placed into the
pressure line by soaking the dripper in hot water first. By placing the dripper
in this way, without glues, solvents, or silicon, we can easily replace them if
they become brittle, split or block. However for any basic blockages, you can
clear the dripperline by just tapping or blowing down the dripper.
We see in Figure 2.5 the pump and the
tank. The tap shown here controls the flow rate by taking some of the pump
pressure away and sending it back into the tank. This also provides agitation and some additional aeration of
the nutrient. We see in Figure 2.6
the wrong way to recover nutrient. By putting a hose in the end, we will cause a
pool of nutrient to back up in the gully, causing root problems because of deep
water. The right way is to have the gully bent a little using a heat gun, steam
from a kettle or a good hairdryer. Try using a header box, or a 2 litre milk
bottle to catch the nutrient and then drain this box or container.
Set-up.
Pick a place that has plenty of light.
Using shade-cloth is usually necessary for hot conditions and what is considered
hot would relate to individual crop techniques rather than Hydroponics.
Try to set up the system on a
reasonably level surface so the legs of the stand can be made to basic lengths
to give the whole stand a uniform 25-mm drop per meter. By measuring the stand
length and making the legs 25-mm shorter for every meter, you will achieve an
overall slope of 1:40. The Channels will bend if insufficient supports are used.
As a guide, 2 part channels (Base and Lid type) require a support every 1 metre,
4 sided down pipe every 1.3 to 1.5 meters and 6 sided channels every 1.5 to 1.8
meters. For long systems, such as commercial benches, it is best to pick a gully
with the least supports required because the costs can skyrocket when nearly
twice the number of stands are needed. If
possible, set up in a position that is not exposed to gusting winds and heavy
rains.
You can set up a float valve on your
tank to replenish nutrient levels with fresh water as the level drops. If you
can pick a place near a tap this may be an advantage.
For a system with up to 30 holes, we
would use about 20 Litres in our tank. (I calculate usually about 650 ml to 700
ml per plant for a home system). Mix 20 litres of nutrient according to pack
directions. Adjust nutrient strength (CF or EC) and nutrient pH if necessary.
Turn the pump on and keep the adjustment tap closed. Then take the two drippers
from one of the gullies and allow to run into a 1-litre container. Time the rate
of flow, and adjust the tap until ¾ litre to 1 Litre per minute is obtained.
Then check that all the gullies have a 1mm nutrient film.
Plant your seeds into a 50-mm
Hydroponic cannabis filled with Perlite and Vermiculite mix. The seeds only need to
be just below the surface, around 1mm deep. Moisten the cannabis with fresh water to
start germination. If starting from seedling, then wash the roots in tepid water
till free of soil. Do not damage the roots. Place in a hydroponic cannabis with
Perlite and Vermiculite Mix. You can keep the seedlings in a warm spot until
roots appear at the bottom of the cannabis, or just place the cannabis with the newly
planted seed into the gully. Maintain the nutrients by changing it every 7-10
days or adjust with electronic testing equipment. (See Appendix on Nutrient
Control) The nutrients and the flow rate need to be maintained until Harvest.
Maintenance.
The only maintenance is to see that
the nutrients are changed every 7 to 10 days or adjusted with the electronic
testers, and that the nutrients continue to flow without any blockages. Normal
crop techniques such as tomatoes trellised to a wire, stake, or lattice will
apply as usual.
Problem
solving.
Root rot occurs when the flow rate or
slope is incorrect. The effect is that the roots are waterlogged by excess
nutrient. The lack of oxygen makes the roots susceptible to rot. Regular checks
of the flow rate will eliminate this problem.
To identify Root rot, there may be the following symptoms: slow growth,
wilting, or yellowing of the older leaves - but always accompanied with
discoloured roots, either brown or black and a mild to strong odour of rotting.
Sometimes the roots are covered in a slimy coating. Call your local Hydroponic
Store. Fungal rots are rare but can
occur, when the water supply is contaminated by Phythium or similar Fungi. This
is true of Hydroponics and soil production, so please do not panic. Regular
changing of the solution usually eliminates the fungal build up, or Ultra Violet
sterilisation of the water supply would be needed to kill Phythium etc.
Generally dam water can suffer this problem as the fungus comes from soil
runoff.
Remember whenever in doubt check the
basics. Light oxygen to nutrient ratio, (In this case, check that the flow rate
is between ¾ to 1 litre every minute). Nutrient strength is not too high or too
low, nutrient pH is between 6 and 6.5 (if the nutrient is only 7 to 10 days old
it should not vary too much) and check the temperature of the nutrient and the
air.
If all else fails - call a Hydroponic
Store. They are there to help YOU!
Growth
Rate.
The growth rate in NFT is generally
very fast. This is due to very high oxygen levels, the ability to aerate, heat,
adjust the strength and adjust the pH of the nutrient. Even without adjusting
the nutrient or heating the NFT is easy to achieve much better plants, faster.
The NFT idea has a flaw. When the
roots get very large they can choke the gully.
This happens when plants such as fast growing herbs and large plants like
tomatoes grow unattended for more than 6 months in a 100-mm wide channel. Growth
rate is inhibited by the choking effect. To fix the problem, use 150-mm wide
gully wherever in doubt. 150-mm gully has more than just one and half times the
base area, it has an air supply that is greater. A 150x75-mm gully has more than
double the air space of a 100x50 gully. Even if the root mat becomes thick in a
150x75 gully, no problems develop unless plants are grown to extremely advanced
ages.
Heat
and Cold Control.
Heating the nutrient becomes
advantageous when the temperature of the nutrient drops below 15 degrees
Celsius. The optimum for growth is 20-25 degrees Celsius.
If a small 20 to 80 litre reservoir needs heat, a 150-Watt aquarium
heater with a thermostat is ideal. Set the temperature in-between 20 and 25
degrees for best results. For tanks up to 160 litres use a 300-Watt aquarium
heater, and for larger tanks, there are some excellent custom made heaters from
1500-Watt to 2400-Watt. The element is designed specifically for your tank.
These are the most efficient way of heating up to 5,000 litres without getting a
heat pump. If cooling is required,
refrigeration, ice, and other methods are generally inefficient or ineffective.
Try setting up a fountain or jet of water (venturi system) off your pump
pressure. This will cool the nutrient as it falls through the air (as well as
adding oxygen to the nutrient). It only takes a little imagination to increase
the cooling effect, with a fan (If you have your tank in a tank room this is
easy) or more ventilation over the tank on hot days. When in trouble, call a
Store.
Suitable
Crops.
In the 100x 50 Channels you can grow
leafy vegetables such as lettuce, beans, broccoli, Brussels sprouts,
cauliflower, celery, cress, mustard, endive, most herbs if short term (because
of smaller root systems), okra, peas, schallots, silver-beet, spinach, squash,
and many other medium sized plants. In
a 150x 75 mm channel, you can grow all the above plus, tomatoes, cucumbers,
strawberries, beans, cabbage, capsicum, eggplant, longer term herbs, marrow and
melons, pumpkin, and anything that grows above ground (i.e. not carrots), and
will be grown for up to 18 months. (Use common Sense. If the root system is
getting too large, you should remove the plant. Some success is reported when
trimming the root systems of herbs, as many varieties do not exhibit large
amounts of stress when this is done carefully.) Ensure all the plants have good
ventilation and light. This is determined by hole spacing. Fancy lettuce can be
spaced 200 or 250 mm apart, head lettuce and most vegetables at 250 mm, but a
tomato, climbing bean, cucumber or similar large plants really needs 350 to 450
mm spacing as their leaves take up too much area. Don’t forget how much root
area will be taken up as well.
Set-up
Costs.
A parts list for NFT is usually very
simple. You will need a stand, Hydroponic channels, end caps, a catchment box/
header box and drain system (preferably with a filter system of a simple
design), tank, pump, feed-lines, seed raising pots and seed raising mix, and
nutrients. A pre-built system of about 30 plants should cost around $400.00. To
do a proper system add $90 for a nutrient strength meter and about $20 to $90
for pH test equipment. These are optional extras that will get you extra growth.
(See Appendix on pH and CF)
Running
Costs.
If growing around 30 plants, with a
20-litre tank, you could change the tank every 7 days and work out how much
nutrient will cost. E.g. Optimum Grow 2L approx. $20 per pack would make up
about 200 Litres, or about 10 weeks of nutrient changing. Accent Culture ‘S’
1 kg (a powder, you mix up liquid concentrate yourself) approx. $20 per pack
would make up 400 litres and give you about 20 weeks worth of changing.
For real budgeting, a $40 pack of
culture ‘S’ would give you 110 weeks worth of nutrient changes, or about 36
cents per week.
A pump is the only other real cost.
For this system a little 600 Litre per hour pump draws about 10 Watts. Running
24 hours per day, 7 Days a week would cost you about 18 to 19 cents per week to
run. THE RUNNING COSTS are the real advantage of a NFT System!
Options.
Trellising the channels or arranging
them on an A-frame is very difficult in soil. It is a great way to grow in
Hydroponics once you realise the difficulties and cost of these systems. First
of all is light (remember the BASICS) If you have your channels above one
another you will have great plants on top, but plants that look sick beneath.
Make sure the front of the trellis faces north (i.e. runs east to west). You
need to allow more space in a trellis than in a table, because the sun may reach
all the plants except during the morning and afternoon, when it is at right
angles to the kit (i.e. from the east and west).
A-Frames are best-set facing north south, so one side gets the morning
sun and the other gets the afternoon sun. You will note less response this way.
Trellising and A-frames naturally require much greater pump pressure, as
the nutrient must be pumped to a greater height. In all cases, it will cost more
to set up and run. Also, if you intend to link the gullies together, ensure the
total run does not exceed 12 meters or the oxygen levels in the nutrient will
drop beyond healthy levels, and plants will not grow very well. Adding extra oxygen to add growth is always an advantage. You
can use three methods. Either use a larger capacity pump and have a jet of water
into the tank (like adding a venturi or a waterfall effect), use an aquarium air
pump and bubble air into the tank through an air stone, or buy a pump with a
built-in air tube that will suck air into the feed line.
Heating is always advantageous if your
nutrient is going to be cooler than 15 degrees Celsius. This will happen usually
if the air temperature drops below 18 degrees Celsius. See heating and cooling
control above for the advantages. Float
valves, like a toilet cistern; help keep the volume of water at a set level in
the tank. Ideal for maintenance free systems, it makes it more secure if you go
for travels.
Removable lids are an advantage if you
have to clean the system and you have no plants growing in it at that time.
Apart from this, mostly, plants are in the system most of the time, so you
can’t remove the lid without flipping your plants out. The channels rarely
require cleaning inside except for a wash out from the top with fresh nutrient
if there are plants in it or fresh water if there are no plants in the system.
The drawback of the removable lid design is that the lid can flip off if plants
are top heavy, leaving your plants on the ground, and that extra supports are
required, (every meter at least) or the gully will sag and cause ponding and
root rot. They are never cheaper in terms of cost, because they cost more to
support.
Round storm water pipe, a round pipe
is not NFT, because the pipe cannot produce a Nutrient film. Roots will form in
a ball, instead of a mat. There will be much less oxygen in a root ball, and
some of the roots will be in air, and some under water. To use this type of
pipe, use a UV stabilised plastic (most pipe is not UV stabilised because it is
meant to be under the ground) and always use a flood and drain approach. (See
Flood and Drain and DFT) Dosing systems will work very efficiently with NFT.
These systems test the nutrient and automatically add nutrient when required.
Dosing systems need a float valve to be effective, and start from around $500.
Variations
on Materials.
Lead - Lead is a filler used in the
recycling process with most plastics. Unless a plastic is termed food grade, it
will most likely have lead in it. Leaded plastic pipe and plastic containers
should be illegal to grow plants in, and moves have been made in Australia to
make sure it is. However, legislation will be a few years off yet.
UV stabilisation - UV stabilised
plastic will not crack in the sun. It makes sense to choose this type of
material over non-stabilised plastic. Black
and white co-extruded gullies - There are brands of Gully that has been made
with a black interior. I have seen farms with this type of gully, and they have
nearly no algae in the gullies, and tremendous root growth due to a darker
interior. This type of gully is also grained to provide better nutrient flow.
This seems to produce less pooling of nutrient, and better roots.
Generally, this is called Panda Gully, because it is black and white. One brand
even has sloping sides to provide rain runoff and extra airflow around the lower
leaves of lettuce and such. It is probably the best-designed gully I have seen.
Conclusions.
NFT is easy to run, cheap to run, low
maintenance, and generally problem free.
Set-up costs are reasonably low, and
little media has to be used to start the plants off. A very good system for
beginners, and advanced growers alike. I like the system. I recommend it.
SYSTEM THREE:
Flood And Drain
SETUP COSTS AVERAGE.
RUNNING COSTS AVERAGE.
EASY TO BUILD SOME PLUMBING.
EASY TO RUN EASY.
MAINTENANCE FREE VARIES BETWEEN TWICE
OR ONCE PER WEEK.
RESULTS EXCELLENT.
Ingredients.
Container or tray to be Flooded (Food
Grade Plastic or Fibreglass).
Irrigation Lines.
Upper Level Drain System.
Lower Level Feed System.
Tank.
Centrifugal Aquarium type Pump.
Filter.
Expanded Clay or Large particle (10-15
mm) Medium.
Nutrients.
Concept.
Flood and Drain uses two cycles to
feed oxygen and Nutrients to the roots. These are the Flood Cycle, and the Drain
Cycle.
FLOOD
CYCLE: To get high oxygen into the root zone, we
can flood the root zone with nutrients, and expel all “dead air” from around
the roots.
DRAIN
CYCLE: After the Flood Cycle (2 to 15 mins) we can
drain the nutrients quickly to draw or “suck” fresh oxygen into the root
zone as the nutrients drain out and at the same time, leave the roots damp with
nutrient. (15 to 45 mins) Sound Complicated? It’s as easy as Pump on and Pump
off !
Design.
To Design a Flood and Drain System we
have to pump from a reservoir into the growing container or tray. We usually do
this by pumping in at the lowest point. See
Figure 3.1 (The Flood Cycle)
The overflow in Figure 3.1 is the
drain point during the Flood Cycle. This ensures the Growing Container does not
overflow with Nutrients. The Pump is on and the Pump power keeps the nutrient
“up” in the container. The
Nutrients Flow in and fill all the spaces between the Expanded Clay and Soak the
Roots with Nutrient. Note that the Nutrients are never Still during this Cycle.
They are flowing up and out, through the over flow. Dissolved Oxygen levels in
the nutrient are high because the nutrients cannot stagnate.
During the Drain Cycle (Figure 3.2), the pump switches off, and gravity
forces the nutrients back through the pump into the reservoir. There is a filter
to stop any damaging particles getting into the pump. As gravity drains the
nutrient, the spaces between the Expanded clay are left empty, and air rushes
into the spaces left by the receding nutrient.
The Flood Cycle should only be as long as it takes to fill the growing
container or tray, and the Drain Cycle should be at least twice what it takes to
drain the container. Usually 15 minutes on and 45 minutes off is enough. If any
root problems occur, lengthen the drain cycle. During the night hours only have
one flood cycle in the night, and one just before dawn. If heat is necessary,
flood as normal during the night, but have one longer drain cycle during the
morning and one in the afternoon to add extra oxygen.
Set-up.
The Growing Area should be set up with
a pump connected to the inlet, and an overflow as shown in figure 3.1 and 3.2.
The pump should be a submersible, and
although you might think a larger pump than usual is necessary, it doesn’t
usually hold true. If the pump has to pump high, measure the distance between
the height from where the pump will be in the reservoir, to the height where the
overflow will be. We are only interested in height vertically, not distance
horizontally even if the tank and growing area is several meters
away(horizontally) from each other. (The
following is an approximation of pump pressure only. It can vary in practice).
If the height of the system was 1
meter,
and you have a 600 litre per hour pump
with a 1.4 meter “head” of
pressure,
then you will have 0.4 meters of
pressure to fill the flood area 0.4 x 600L ph = 240 Lph.
240Lph =60 Litres per 15 mins, so you
can flood a chamber of approximately 60 Litres if you flood for 15 mins.
Tank size in Flood Systems should be at least 1 and a half times the
growing area. (Expanded Clay takes up a lot of the volume, so the nutrients
required to flood the area is not even ¼ of the growing area size) Inlet: The
Inlet should be at the lowest possible point to drain the growing area. Wherever
possible, complete drainage will give you the best results. Some sort of Screen
should be placed over the inlet so that it does not become blocked with expanded
clay during the drain cycle. If the screen is fine (like stockings), it will
block with the fine particles and the system will remain flooded. Use a wide
mesh made of plastic like a ¾ inch Phimac Foot Valve Screen. This is large
enough to not block, and small enough to block expanded clay from falling into
the inlet. (Never use metal in Hydroponics. Use plastic parts, or stainless
steel, because metals will react with the nutrient) Overflow: See dig 3.1 and
3.2. Set the overflow at least 1 cm below the top of the media, or the plants
can be dislodged from the expanded clay when it over-floods the media. Again,
use a screen so that the expanded clay will not fall into the overflow.
Use an “in-line” filter between
the inlet and the pump to collect any fine particles. Clean it regularly if you
notice it is picking up any expanded clay particles.
If you have any problems, discuss it
with your local hydroponic store.
Propagating.
Propagating in Rockwool cubes, or
perlite mix is required to give the seeds a chance to germinate and develop a
root system. Flood systems usually don’t give a good result for propagation
because the medium has very little water holding ability. For striking cuttings,
inset cutting into expanded clay, and put some liquid rooting hormone into the
reservoir. Cuttings strike very well this way, but you should shield them from
very hot or dry conditions or bright sun. Misting
them should stop them drying out before the roots have developed.
Maintenance
and Problem Solving.
I usually would advise people to keep
an eye on their plants. If the stem and leaves wilt, then increase the number of
floods. If the leaves wilt with yellowing of the leaves; you may have too many
floods and the roots are drowning or rotting. Immediately increase the amount of
time between flooding. As a guide, try flooding 15 minutes out of every hour, by
setting a household timer such as a Kambrook KD84 (15min increments) to that
period. I miss out 3 to 4 floods a day, during the night, or during the morning
or afternoon. The reason I do this is to give the roots a chance to get a bit
more oxygen. But if the plants are cold at night, and I am heating the solution,
I would not give them any breaks during the night, using the morning or
afternoon to give the system a break. If I have a choice, then breaking the
flood times during the day is always my second choice.
Nutrient Changes should be performed
regularly, if you have no electronic test equipment. For a 20 to 40 litre tank,
feeding around 2 to 10 plants, I would change every 7 to 10 days. If more plants
are using the solution, then change more often, and use common sense. If your
plants start looking less than perfect, try changing more often. Take a sample
of your nutrient into a hydroponic store and ask them to test it for you. take a
fresh sample from when it was first mixed up, and a sample before dumping. This
will give you reference to how the
nutrients are going. Flush the expanded clay every 4-8 weeks with a weak
nutrient, just in case any nutrients build up on the expanded clay. This can
occur if the plants use a lot of water, and leave the nutrient behind. This is
called salt build up. Some people get this problem, some don’t. Clean the
filter if the system is not draining quickly.
Growth
Rate.
This system is known for unbelievable
growth rates when it is really well run. Even
without nutrient management, and control, the high oxygen ensures good growth
rates at all times.
Heat
and Cold Control.
Since this system uses intermittent
pumping cycles, the only time we have complete control of the nutrient is when
the nutrient is flowing in the growing container. When the Growing container is
drained of nutrient, the temperature is affected more by the air temperature. If
heat or cold is extreme, consider using more flood cycles during that period of
the day and less at other times. An example might be, very cold at night, and
medium hot in the day around noon. Then
you could flood more at night and miss a flood in the morning and one in the
afternoon. Don’t flood for longer, but have less of a period for draining.
Heating the Solution is an effective way of controlling the temperature.
If the weather is hot, you will find that nutrient will cool enough generally
because the nutrient flowing into the growing chamber is falling back into the
tank through the overflow, and the aeration is cooling the nutrient enough.
Further Aeration should cool the nutrient further if required.
Suitable
Crops.
Flood and Drain is excellent for
permanent crops, Herbs, Flowers, and all crops. Harvesting plants usually means taking some of the media with
the roots, so I do not usually grow short-term crops in flood and drain, but it
works very well. If root crops are grown, make the expanded clay a fine grade,
and keep flood cycles far enough apart so that rotting does not occur. Root
Crops will do better in a Pot with Perlite really, but you can give it a try.
Striking cuttings with a Flood and Drain System is excellent, just add some
rooting hormone to the nutrient solution. Too many floods could lead to stem rot
in this case so halve your flood cycles, or keep a good eye on your cuttings.
Set-up
Costs.
Pump, Expanded Clay and Growing trays
make this a medium cost system to set up. Some
trays can cost a lot. For Price, if you are setting up the system yourself, use
plastic tubs and more of them, than trays. Trays are cheaper when buying a
complete kit, because stores find the labour time shorter and less framework to
build more inexpensive, and generally discount the pump and media. A small tub
system should cost less than $200 and full Trays up to 1 square meter in size
should only cost $350 to $400. They are excellent when pre-built, but check they
have included a filter for the pump, (unless they are the top feed type).
Running
Costs.
Running costs are medium because the
larger tank holds more nutrient and should still be adjusted or dumped
regularly. Also the replacement of media adds cost because when plants are
removed, as they can take some expanded clay away with their roots. Offset
against running costs is the excellent growth rate. I would rate this system a
top performer. So yields can offset the cost.
Options.
Flood and Drain Systems have a
disadvantage in that normal automatic filling systems using float valves are
more difficult to set up as the reservoir will be lower during the flood cycle
and higher after the system has drained. We should set up the float at the
minimum level, and ensure no leakage around the float valve fitting. Fig # 3.3
The different reservoir quantities at flood time and drained time can make
nutrient dosing computers difficult to organise as it may adjust the tank and
find that during a different cycle the nutrients need a radical readjustment
because the total volume of the tank changes.
However, using diagram #3.4 we can see
a timing system for dosing equipment that should optimise the computerised flood
system.
Variation
on Feed System -.
A flood and drain system using a top
feed. Nutrient pours into the top at a faster rate than the smaller holes at the
bottom can drain. The overflow is
still present, but when the pump switches off the system drains slowly. The
bottom holes can block with small media particles, so ensure there is a drain
coil (not a foam or cloth filter) around the drain point to keep them clear and
allow you to check them for blockage. This system has the advantage of saving
your pump from grit and cleaning, but is less responsive if the system does not
drain quickly enough.
Variations
on Materials.
There are purpose built flood trays,
which drain completely with no pooling at the base of the growing tray. These
are better than normal buckets, boxes or other containers. For DFT or Deep Flow
Technique, we can use channels, or even round pipe, but flat bottoms make it
easier to plumb fittings, and round pipe can only be fitted at the end caps. See
DFT later in this book. For
efficient draining, ask for a ¾ inch Foot Valve (Screen Only), made by Philmac.
They are a drain cover with openings too small for expanded clay, but big enough
to drain quickly. They are also, very easy to plumb.
Conclusions.
Flood and Drain is a very high powered
system, and will give you much higher yields than similar systems. It is too
tricky and expensive to consider on a large scale, and running costs versus
yield is lower than NFT. You will have fun with Flood and Drain, because there
is more experimentation for the grower than with normal systems, and root size
doesn’t matter as much as NFT as the roots don’t usually choke up when large
like they can in small NFT channels. One of my favourite systems for those who
like to tinker around, and “play” with their plants.
SYSTEM FOUR:
DRIP SYSTEMS
SETUP COSTS AVERAGE TO LOW.
RUNNING COSTS AVERAGE.
EASY TO BUILD LITTLE EFFORT.
EASY TO RUN EASY.
MAINTENANCE FREE VARIES BETWEEN TWICE
AND ONCE A WEEK.
RESULTS VERY GOOD.
Ingredients.
Media, such as Expanded Clay, well
draining.
A Container for the Media - Plastic
lined containers, Fibreglass trays, Plastic or Polystyrene Boxes, Pots, Buckets,
Planter Bags etc.
Feed lines and Drippers
Drain/Returns
Pump
Reservoir
Nutrient
Concept.
The Plant is grown in a media that is
has low water-holding capacity, and large particles, so air can move around the
roots. The Plant is fed by pumping the nutrient through dripper lines. By
altering the amount that is feeding the plants or by using a timer, the oxygen
to nutrient ratio can be adjusted. The ideal situation is to keep the roots
reasonably moist, but not wet. Results are also good if excess nutrient is used
to feed the plants roots, followed by a break for them to drain off a little.
The plant roots are never immersed in nutrient at any time.
Design.
Drip Systems give the greatest
latitude to the designer. Almost any container can work as long as it is a food
grade Plastic, Fibreglass, Polystyrene, Stainless Steel or other non-phytotoxic
container. All you have to achieve is moisture at the plant roots, and have the
container drain well to provide good oxygen levels around the roots. As the
plant grows, the amount of nutrient required may increase slightly as the plants
consumption rate goes up, but oxygen levels must never be compromised.
Drip either onto the surface of the
media or just below if you wish to avoid algae on the top of your media.
Ordinary garden type drip irrigation fittings seem to work very well. Ensure
that drain fittings do in fact drain, and will not get clogged up by media or
roots. Any nutrient pooling in the bottom of the container due to incomplete
drainage can lead to root problems, as this nutrient can become stagnant, and
rot the roots that grow into it. Do
not use brass or other metal fittings in your design.
Set-up.
Gravity is the best drainage system,
so set up your system with the tank at the lowest point, and feed from that tank
directly to the plants. Use the
pressure of a pump to feed the dripper as a pump is easily controlled, and the
pressure keeps blockages to a minimum. Remember,
Gravity is not the best-feed system, as Gravity is plagued with blocked feeders.
This is because any small particle (like bits from a plants old roots) that may
be in the nutrient will be moving slower in a gravity fed system, and if the
particle finds a place to settle it can create a problem, because as more
particles build up the end result is a blocked up feeder or dripper. And
besides, I can’t see the need for an upper tank and a lower tank.
Pump running costs are generally very low and using a larger pump, less
often, just to fill an upper tank, never saves you money.
Propagating.
Propagating in Rockwool cubes, or
perlite mix is required to give the seeds a chance to germinate and develop a
root system. Drip systems usually don’t give a good result for propagation
because the medium has very little water holding ability.
Maintenance
and Problem Solving.
Generally, 15 minutes out of every
hour works best. I have seen incredible variation, from adjustable drippers
running with a very slow drip continuously, to gushing flow for a minute every
hour. COMMON SENSE APPLIES. The roots need to be moist (and never wet and never
dried out). They need oxygen. Try to give good drainage, and good amounts of
nutrient, but always watch the plants for changes. It will help to get individual advice from a store, because
of climate, system design, and crops grown.
Change the nutrient regularly, if you
have no test equipment. For a 20 to 40 litre tank, feeding around 2 to 10
plants, I would change every 7 to 10 days. If more plants are using the
solution, then change more often, and use common sense. If your plants start
looking less than perfect, try changing more often. Take a sample of your nutrient into a hydroponic store and
ask them to test it for you. Take two samples to the store. The first sample
from when the nutrient was first mixed up (start-up sample), and a sample before
dumping (end sample). This will
give you a reference to how the nutrients are going. Flush the expanded clay every 4-8 weeks with a weak nutrient,
just in case any nutrients build up on the expanded clay. This can occur if the
plants use a lot of water, and leave the nutrient behind. This is called salt
build up. Some people get this problem, some don’t.
Too much feeding will usually cause
root rot, and the older leaves will yellow, and the roots will go brown or black
and start to smell. Plants may wilt. Be careful that you do not interpret wilt
as under-watering. Under watering causes wilting at more specific times, such as
the hottest periods of the day, and during the periods before their next
watering. Generally stems wilt with under-watering, and the stems are less
likely to wilt with root rot.
Growth
Rate.
Drip systems are generally very good
for getting results, without too much design problems. If Oxygen is high in a
fast draining medium, there is no reason that this may not produce very fast
healthy plants.
Heat
and Cold Control.
Heating and Cooling Techniques are
applicable to Drip Systems, and are especially effective if the nutrient is
continuously dripping, but this is difficult as roots may become too wet and
Oxygen levels could be too low. Perhaps
night feeding can be stepped up if the temperature is particularly low, or a
greenhouse arrangement would be required. Cooling can be effective, but again,
it will require the nutrients to circulating as much as possible Suitable Crops
Drip Systems excel because you can build your system to suit the size of the
plants’ root system. As a rule, the longer the plant is to grow, the larger
the growing space required. Herbs and Flowers are good in Drip Systems, and
Lettuce or Tomatoes would merely need smaller root areas. I like using 20-30
Litre Crates for drip systems generally, but ensure that the plastic is not
reground recycled plastic, which is usually toxic to plants.
Set-up
Costs.
The set-up costs are inexpensive,
except when using growing containers, which are very large. In these cases, the
amount of expanded clay per plant makes the cost rise. Don’t go over board on
the size of containers, as hobbyists usually pick the largest container
available. Even Food Grade Plastic Buckets work well for drip systems. About $40
will get you a 40 to 60 Litre sized bag of expanded clay, and you can always ask
the store for $20 worth and so on. Apart from containers, expanded clay and
three or Four Dollars of Polypipe irrigation, the only concern is the pump.
Pumps will work for years if you buy a good one. Cheap ones usually work for a
few months and give up. What you are interested in is not necessarily the flow
rate but the Pump Head. This is the measurement of pressure, and the maximum
height a pump will lift nutrient to. So ask a store what the pump head is, and
wherever possible, keep your system low, or keep your tank up off the ground,
and this will save you money in pump size.
Running
Costs.
Nutrients are inexpensive. About the
same nutrient consumption as for the NFT system mentioned previously. For 2 to
20 plants, a $40 pack of Accent Nutrients (makes 2200 Litres) will last about 1
to 2 years. Pumps consume about 1 cent of electricity for every 10 hours
running, so running costs overall will be very low indeed.
Conclusions.
Drip Systems make a very versatile
system for both long term and short-term crops. It is also the best
recirculating system for the do it ‘yourselfer’ to make, and usually can be
made from inexpensive materials, and can be expanded easily. I recommend this
system for those of you who want to grow large plants quickly, with no troubles
either with design or maintenance. As always, draw up your system as a sketch
first and ask an experienced grower or a Hydroponic Store before purchasing
materials or making the first hole. This will be like insurance, that the whole
system will be designed to grow well year after year.
SYSTEM FIVE:
ROCKWOOL
SETUP COSTS LOW TO AVERAGE
RUNNING COSTS AVERAGE IF ROCKWOOL
REUSED
EASY TO BUILD CAN BE VERY SIMPLE
EASY TO RUN AVERAGE
MAINTENANCE FREE ABOUT TWICE TO THREE
TIMES PER WEEK
RESULTS GOOD TO EXCELLENT
Ingredients.
Types of Rockwool
Rockwool comes in different sizes and
shapes, as determined by each individual manufacturer. This can often become a
headache for the grower if his design incorporates certain sizes. I can explain
that Rockwool comes in slabs, thick, thin, wide and narrow, wrapped slabs so
growers can grow directly into the slab, and unwrapped so the slab can be put
into pre-designed troughs and channels. Also
available are small propagation blocks, for germinating seeds, and medium sized
cubes for propagating cuttings or for growing seedlings previously grown in the
small blocks.
Concept.
Rockwool is a fibrous product that
appears a little like insulation slabs. It is made by spinning liquid rock and
collecting the strands like fairy floss at a carnival. The fibres of rock in the
slab hold large amounts of water, without depriving the roots of oxygen, and
will drain well because of its density. It
comes in two grades and the two grades are vastly different, although the
manufacturing process is the same. Horticultural Rockwool is made from basalt
rock, a combination of rock, limestone and coke. The best Rockwools are made
from Volcanic Basalt. The insulation grade and cheap grades of Horticultural
Rockwool are made from the slag from a blast furnace, often containing a lot of
metals such as steel, iron, or copper, occasionally minute contaminants, and can
affect nutrient solutions, as well as having a distinct problem with wetting
down due to oils in the fibre. You can pick these grades by the requirements to
wash or rinse the impurities from the Rockwool first, and this Rockwool will
often foam from the wetting agents that are mixed into them. (Do note that
Rockwool should be rinsed no matter what grade, as uniform moisture levels are
harder to achieve if this is not done first)
In Horticultural grade Rockwool, such
as Grodan, Pargro, Esplan and others, the Rockwool fibre can be placed in bags,
containers, troughs or other well draining types of systems. Rockwool is best if
over irrigated with nutrient and then allowed to drain as the slabs will shed
excess moisture till an optimum moisture level is reached. Small Rockwool cubes
are great for propagating seeds and cuttings as the moisture retention levels
are high.
Design.
Rockwool is best if fed by drippers
until uniformly moist. However, because Rockwool will maintain an optimum
moisture level if overfed and allowed to drain, we must ensure good drainage.
Rockwool Slabs can be placed in plastic troughs or plastic lined troughs, and
inclined so that they drain well. Nutrients
can be recycled if pH testing is done regularly. The Slabs can come wrapped in
plastic as shown in figure 5.5 and the plastic wrapping acts as the growing
container. A sheet of plastic is used to collect the nutrient and send it back
for recycling.
Other designs also make use of the
drip system by cutting the slabs into blocks and slipping them into pots or
buckets (again ensuring adequate drainage).
You should use a pump. Set up a drip system similar to Drip systems I
described earlier. By switching on the pump for 30mins and checking when the
Rockwool begins to dry out you can locate the best irrigation cycle for your
system. Remember, Rockwool holds a
lot of moisture, but is difficult to saturate with too much nutrient as it
drains away. The other advantage is that Oxygen is still trapped in the Rockwool
fibres so plants can be over-watered if desired. Be careful not to let the Rockwool dry out too much as it can
be a little bit harder to rewet evenly, and the roots will die back if they
encounter dry spots. If re-wetting
is required, flushing the Rockwool with a soil wetting agent can work, but good
results have been obtained, (but only second hand knowledge to myself) using an
organic liquid detergent such as L.O.C. or similar as these organic detergents
don’t seem to hurt plants. Commercial brands of detergent can contain a lot of
other compounds, but the organic ones are simple phosphorus compounds with
organic bases, (and keep your pH down too.) Some people have good results with
Flood and Drain Systems and Rockwool. Unfortunately,
I have never done this myself, so although it can work according to those who do
so, I cannot comment on it. I would be very concerned with the amount of water
being forced into the Rockwool, and it may take a longer time to drain than a
drip system. I can imagine that the Rockwool would certainly be more evenly
moistened by flood and drain systems than in drip systems.
Maintenance.
Rockwool can build up unused nutrients
in the form of salts. By regularly flushing the Rockwool with half to full
strength nutrient, these salts will dissolve and be washed away. Plain water
flushing is not recommended as it can stress the root system and even cause
damage, especially at the sensitive root “hairs” that can explode with the
sudden change in osmotic pressure. pH
is critical in Rockwool Systems. If recycling nutrient pH should be checked
every day if possible, but at least twice a week. (Run To Waste Systems:
Rockwool can be watered till 5 to 10%
runs to waste without recycling. Ensure a sample is taken from the root zone by
inserting a syringe into the Rockwool and drawing out some nutrient. Syringes
can be arranged through a Hydroponic Store, and sometimes they’ll do a test
for you.)
Growth
Rate.
Growth rates in Rockwool vary between
good and unbelievable, as long as pH adjustment and regular flushings take
place.
Heat
and Cold Control.
Heating and cooling usually applies to
nutrient heating or aeration as we discussed before. Sometimes slabs can be
placed on heated pads, or heating coils or hot water pipes that are in a bed of
sand. This can provide the bottom heat between irrigation, but only really
applies in a commercial situation. If using heated blankets under a bed of sand,
ensure a “shocksafe” is installed in case of a shorted wire. In one case of
the use of electric blankets I know of, the only thing that saved the growers
life was that his dog touched his plants first, and was electrocuted in front of
him. Be careful with cheap electrical solutions. Sometimes they treat you like a
cheap parachute!
Suitable
Crops.
Most common crops are Tomatoes, Herbs,
Flowers, Cucumbers, strawberries (Be Careful with strawberries. They hate salt
build-up and are susceptible to crown rot in continuously flowing media
systems). You can also grow most medium to long term crops including good
results with root vegetables. Short term crops like lettuce will grow, but you
will go through more Rockwool slabs, and it will cost more than a simple Perlite
and Vermiculite mix without any advantages.
Set-up
Costs.
Rockwool Prices vary from town to
town, and brand to brand. Check with a Hydroponic Store, however, costs are
similar to a drip system to set up.
Running
Costs.
Rockwool should be reused only if the
root systems have not destroyed the fibrous nature of Rockwool, or if disease or
salt build-up has been a problem. If so, you must factor about 1 to 3 crops
before replacement in imported Rockwool, or just the one crop in Australian
Growool (could be two if you are on a budget).
Options.
Granulated Rockwool is often
available. This is like a shredded or flock of Rockwool and many orchid growers
use it in pots, because it is not in a slab/block form so it fills the pots
easily.
The Rockwool cubes or blocks suit both
propagation of seedlings, cuttings and cloning procedures. The cube protects the
roots, so when the cube is transferred into a Rockwool, Expanded clay, Perlite
System, or even soil growing there is little transplant shock. This is because
the roots are not disturbed during transplanting. Soil Growers like them because
they are a better economic choice than Peat pots.
Warning to NFT growers
Rockwool cubes are not compatible with
a standard NFT system. Sometimes a cyclic NFT (timed on and off) can give good
results. Always ask your Hydroponic Store for Advice.
Conclusions.
Rockwool requires pH monitoring. Apart
from that, a hobbyist can use Rockwool with surprising results. The Rockwool
acts like a buffer to any changes such as pump failure (very rare with good
quality pumps), and holds excess moisture without depriving the plants of
trapped oxygen in the fibres of the Rockwool. A good system, with too many
variations in ideas to list. Great for the experimenter.
Other Systems:
Aeroponics
Aeroponics is growing plants in Air.
The Roots are suspended in the air, in the dark and MISTED with nutrients. The
roots have maximum oxygen and a damp atmosphere in which to grow. I emphasise
Misted, because I have seen systems do considerably worse than a simple drip
system, because the spray was sharp and damaging to the roots. Aeroponics
requires specific misting emitters to softly apply nutrient to the exposed
roots, and a high-pressure pump to do it. If you can't deal with the cost of
this system, don't bother trying to use lower pressure, build a drip, flood, or
NFT instead. The results from Aeroponics show that this is the ultimate in all
systems. There are some aeropots that are built for Aeroponics, that have
overcome the problems with Aeroponics plant support. Use Expanded Clay in these
pots and the roots will come out of the sides very quickly, develop to be huge.
A humble lettuce can grow roots to 5 foot long, so ensure you have some depth
for the roots to grow in the aero-chamber.
Drip
Aeroponics.
is a new term, and is a fantastic
development. Drip Aeroponics uses the common small submersible pump, and drips
nutrients through an aeroponic or garden cannabis of any size. The pots are filled
with expanded clay. By suspending these pots the roots grow out the base and
hang in the air. The Nutrients exit the cannabis the same way, and dribble down the
roots. If the drip system uses sufficient breaks to let the roots
"air" of any excess nutrient, the results are Aeroponic, or at least
resemble Aeroponics. Try it out! I nearly made it one of the 5 Systems. I will
be writing more on this system if we can try a large trial kit to test it out on
a mini-commercial level.
DFT.
DFT stands for Deep Flow Technique.
The best way to explain DFT is that it is a Flood and Drain system with no
media. Usually a DFT system is a trough much like a NFT system, except the roots
are submerged by about 40% of the gully height with nutrient for about 15
minutes and allowed to drain down to 1mm deep for the next 15 minutes. The Flow
of Nutrient is designed so that the plant never begins to float, the nutrient at
any point does not have a chance to stagnate, the roots are not flooded
(drowning) for too long, the roots never dry out, and the system is heavily
aerated. Designing a system to do this is similar to flood and drain and has
given fantastic results to some people, and not so terrific results to others.
The trick is to obey the rules of Hydroponics. LIGHT, OXYGEN TO NUTRIENT RATIO,
NUTRIENT STRENGTH, NUTRIENT pH, AND TEMPERATURE. I have included below a design
of a system I have used. It works very well. Figure 6.2 DFT Gully, Feed and
Drain System, showing the gully to be level, not sloped, and that there is a
minimum level of 1mm in the system.
Bag
Culture.
Basically a drip system, used by
commercial growers. Planter Bags filled with Media such as Broken up or loose
Rockwool, Perlite (no Vermiculite), Sand, Gravel’s, Expanded Clay etc., are
suitable. Use a roll of heavy-duty plastic on the ground and have a slope on the
ground so that excess nutrient flows to a point that you can run the nutrient
into a plastic gutter or pipe to recycle. Drippers are run to each Bag. Use a
dripper that can be adjusted for each plant. Can be effective, but prone to
disease, pest and nutrient problems as all sorts of things can end up in the
tank, even the enemy of Hydroponics, the dreaded dirt!
Soilless
Culture-Plant Nurseries.
A combination of Disease free river
sand, bark or chip, and other non-soil materials, with a trace element mix, slow
release fertilisers have worked a treat for nurseries. These nurseries plants
are always in demand and are usually better quality. It takes more time to set
up a mix, but the pH is easy to keep consistent, and results pay dividends. If
you are a Horticulturist, you can read a mere page or two of your textbooks to
get a mix planned. If you have problems, give one of the large Hydroponic
Companies a call. They may be able to help with a mix. Other types of systems
have not been used enough to give certainties. Bag culture is too expensive for
common plants, but super advanced, or mature trees can get a boost from
nutrients and an additive called Superthrive. Superthrive can get two years
growth into one! One way is the sand bed. Sand beds fed with nutrient provide
capillary nutrient feeding when pots are placed on the sand, but algae can grow,
and diseases if Sand is very wet on top. Clean up for Sand beds is messy.
Otherwise consider overhead sprinklers, with recycling via the plastic sheeting
or under gravel drain coils. These could work well.
Soilless
Culture-Landscaping.
Landscaping, without dirt??? Yes it is
possible, and even practical. If you consider how well plant growth can be
controlled in Hydroponics, as well as computerisation from around $500 to $600,
why not? For Landscaping, the design is critical if nutrient is to be recycled.
Plastic containers and fibreglass enclosures can be sunk into | | | | |
