NFT DFT
NFT SYSTEM
NFT (nutrient film technique) operates on the theroy of a thin sheet of water traveling on a flat surface touching only the bottom roots of a plant. Many commercial growers use this system.Two good sources for home built systems are vinyl gutter, and vinyl down spouts. The down spouts are probably better because you do not have to construct a top for them, but most are no more than 3 inches wide and restricted to smaller plants. Do not use aluminum gutter or down spouts for hydroponics. It is possible that one might find larger vinyl down spouts that could be used for any size plant.
7/8th inch holes are drilled on the top of the down spout 8 inches apart. This distance will accomidate most plants that can be grown in a down spout. Sleeves made of 1/2 inch thinwall PVC cut 1 1/4 inches long with one end flared out will fit into the holes and give the plant more stability. The down spouts shown are resting on 1 inch PVC with a drop of 1/2 inch/foot to insure nutrient flow. Eash tube is fed with 1/4 inch od plastic tubing. This will give about 1 to 2 quarts/minute nutrient flow which is about right for NFT. On the inlet end a piece of stiff plastic is glued in the bottom half to prevent nutrient from leaking out the inlet end. The outlet end is suspended over a 30 gallon garbage can that catches the free falling nutrient. In the bottom of the can is a 170 GPH submersible aquarium pump. The pump runs 24 hours/day when first planted, and from daylight to dark when the root have begun to grow well. There is a piece of wood tied across the top to prevent the down spout from rolling over as the plants get large.
DFT SYSTEM
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.
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