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This
was the original pioneering hydroponics technique. Although dated, it
is still very popular among indoor horticulturists, mainly due to the
inexpensive cost of setting up a NFT system, but also its simplicity.
The principle is very easy to grasp. The plants are grown in a constant
flow of nutrient enriched water. The water is spread out so as to flow
in approximately 1-3mm of depth over a flat surface. This creates a film
of water, which flows over the root system of the plant. This is not a
rapid flow but enough of a flow that the water is in constant motion.
Water is fed to the table via a submersible pump from the top end of the
table.
As the water is pumped in at one end of the table, it slowly makes its
way to the bottom of the table where it then returns back to the reservoir
in which the pump is submerged. So you get constant exchange of the water
in the reservoir being pumped from one end of the table then returning
to the reservoir via the other end of the table. The film of nutrient
should always be maintained at around 1 to 3mm of water. The roots of
the plant should grow below and above the water’s surface and that
is why the film should be constant, allowing the water roots to develop
below the water’s surface, and also allowing the air roots to grow
above the water’s surface.
The drawback of this system is that as the roots are constantly submerged
in a film of water, this prohibits the aeration to the rootball, which
in turn prohibits outrageous performance. To get over this problem, some
NFT growers put the pumps on cycles, effectively flood and draining their
NFT system. Other growers put air stones in the water reservoir and even
under their plants on the NFT tables. Most NFT growers administer H202
to their tanks but at a very diluted ratio, however, this really needs
to be done on a daily basis as diluted H2O2 breaks down very rapidly and
over the course of 24 hours has completely dissolved its active ingredients.
In using H2O2 in a daily capacity, this prohibits the use of organic growth
promoters and other products that reduce the possibility of bacterial
break out like pythium.
The main disadvantage with NFT systems, especially in a grow room environment
is the fact that pump failure is likely to strike at some point. The reason
this tends to happen is that NFT systems are packaged with small flow
rate pumps; cheap springs to mind but this is not technically fair.
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The
plants only need a small delivery of water at a constant rate and the
small pumps are all that can be used on a small NFT system. Now as the
pump is perpetually on, the pump sees a lot of action over the course
of its life.
This coupled with the fact that you are then adding dissolved salts in
the tank and in turn you are possibly in a hard water area, you get precipitation
of the salts and the calcium that build up on and around the impeller
of the pump. Once this impeller begins to attract precipitation, it is
not long until it either gives up spinning completely or that it does
not deliver enough water to satisfy the plants’ needs, resulting
in crop failure. Pump failure can be overcome through regular cleaning
and maintenance of the pump or indeed regular replacements of the pumps.
As mentioned earlier, these are very inexpensive pumps and therefore can
be regularly replaced without financial worry.
Another downside with this technique is due to the fact that the roots
are constantly submerged in water, so the plants are very prone to bacterial
disease like pythium. Again, this can be overcome via regular dumping
of the nutrient reservoir and adding products to the nutrient solution
that have active ingredients that minimise the threat of root rot and
moulds.
The last drawback is that heavy yielding plants tend to fall over in a
NFT system. This is due to the fact that the roots grow out flat and long
giving the plants no stability. As they grow older and bigger you will
need to support the fruits or flowers otherwise they simply topple over.
Supporting them is easy using yo-yos, string, canes or some growers use
a scroge. This is simply netting stretched out over the growing area.
The plants then grow up through this netting which in turn helps support
the plants.
All of the above to one side, these systems are very productive and are
an excellent inexpensive teaching aid to the principle of hydroponics.
Also with this beautiful innovation the world of hydroponics might not
be with us as this technique was the first adopted and used by many growers
all over the planet, paving the way for our very own hydroponics revolution.
One has to take one’s hat off to the British inventor that pioneered
this technique. I mean, what made someone think: I know let’s grow
plants in a soilless medium using nothing but a film of nutrient to do
it in. Off the wall you could say!
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