DFT (Deep flow technique) Almost identical to NFT, except a round PVC
pipe is used causing the water to be deeper in the center of the pipe.
Under high temperature conditions, this can cause an oxygen deficiency
in the roots, but under normal conditions, the system works very well.
7/8th inch holes are drilled cross ways near the top so a piece of 1/2
inch PVC pipe can slide through 3 or 4 pieces locking them together so
they do not roll. In the picture, the locking PVC is half way down the
pipe. 4 inch thinwall PVC can be used to grow most plants. The roots
will not back up the nutrient as long as no more than 1 to 2 quarts per
minute is used. For the larger plants 1 1/16 inch holes are drilled and
3/4 inch thinwall PVC sleeves are used.
The advantage of the NFT and DFT systens described above is excellent growing conditions without need for medium, plus simplicity. The main disadvantage is the necessity of growing plants in some type system until they are large enough for the roots to reach the nutrient flow, and the short life of the plants should the pump quit or the nutrient be lost.
SLEEVES
The sleeves used in the NFT and DFT systems to hold and stabalize the
plants can be made by cutting 1/2 in and 3/4 in thinwall PVC into 1 1/4
inch piecies, then flare one end by compressing in a vice with a piece
of metal that is round, tapered like a cone and larger on one end than
the PVC tube, until one end expands outward as pictured.
These sleeves will fit good into the 7/8th and 1 1/16th inch holes in
the downspouts and 4 inch PVC pipe.
NUTRIENT TANKS
There
are a number of things that can be used for nutrient tanks. A 32
gallon garbage can that can be purchased from K Mart for $7 or $8 does a
good job. One of the best this grower has found is a 56 gallon plastic
drum used for fruit juice concentrate. It is safe, holds up well in
the sun and can be used in a number of ways. It can be cut half for for
2 26 gallon tanks, can have a hole cut in the top for a 56 gallon tank,
or laid on it's side for a low 50 gallon tank. If available, the used
drums are usually reasonable priced. The one shown was $4. If one
looks in the right places, there are no doubt other used food containers
that would make excellent tanks.
A drum set up and ready to start. Pieces of screen are held in place
with 2 old 1 gallon pots. This keeps debris out of the tank and
prevents mosquitos from breeding in the nutrient. The center hole is
used to add water and nutrients and check nutrient levels is also
covered with a small pot. The tank will be painted white to help keep
nutrient temperatures down.
If this were a cold climate, I would paint it black to try to raise
nutrient temperatures.
The above information is provided for those new to hobby hydroponics and those who might want to try a different system. In some cases the information might not be relevent for use in a commercial operation.
