The Nutrient Film Technique, or NFT, system is one of the oldest and most popular types of hydroponic system, and works by constantly pumping a thin film of nutrient solution directly to the roots of the plants. This film will show you how to set up an NFT hydroponic garden.
Start by placing the top tray onto the nutrient tank, and screw it on to attach it. The top tray is shorter than the tank, leaving a gap at one end for adding water and nutrients. Don't use water directly from the tap in your NFT system. Allow it to stand for 24 hours first, so that the chlorine can evaporate. Use opaque, rather than clear buckets, as light causes algae to start forming in the water. During the 24 hours, the water should also adjust to room temperature, or roughly 20 degrees Celsius.
Water and additives
You will now add the water and nutrients to the tank in stages. Start by pouring in two-thirds of a bucket of water, before you add any nutrients. Most nutrients are supplied in a concentrated form in either a “grow” or ”bloom” formulation each used at different stages of plant growth. Additionally, each formulation is supplied in two bottles marked A and B. The two should never be mixed together in their concentrated form. Give the bottle of Grow A nutrient a good shake, then use a syringe to measure it out. Follow the instructions on the bottle to see how much nutrient to use. In this case we're making a fairly weak “grow” solution for young plants, using only 2 millilitres of grow A and B per litre of water. Add the A nutrient to the tank, and then rinse out the syringe with water. Now add the remaining third of the bucket of water. Add the B nutrient to the tank, using the same method as before. Now add some more water from the second bucket, to mix up the solution even more. Other additives you should put in the water at this stage, are a plant booster and tonic, which also adds beneficial bacteria to the water, as well as a blend of hormones and vitamins to assist root development. Add some more water to mix the solution up again. For more information about additives, watch the film ‘Guide to Hydroponic Plant Food.
Testing the pH level
The ideal pH level you should aim for should be between 5.8 – 6.3, but a slight variance on either side of this is OK. Take a pH reading of the water with a calibrated pH metre. If the pH level is too high, add a small amount of phosphoric acid to the water to bring it down. The acid needs to be handled carefully, as it can be quite dangerous. Follow the instructions on the bottle. Now add the last bit of water, up to the maximum level which is marked inside the tank.
The top tray
You will need a flow pump, to pump the water and nutrients into the top tray. This will have a delivery tube, which fits in a hole in the side of the top tray. Switch the pump on, so that the water flows into the gulleys of the top tray. The tray is at a slight incline, so gravity causes the water to flow all the way to the other end, and out through a hole in the bottom. Next, lay down some nutrient spreader mat into the top tray. The mat spreads the water and nutrients out evenly to form a thin film. Cut the spreader mat into pieces to cover the whole of the tray.
You will need a correx lid over the top tray, to keep the plants' roots in darkness. The plants will be in rockwool blocks, so you need to cut holes the same size as the blocks into the lid. Stagger the holes, to spread the plants out as much as possible. Cut a flap at the end of the lid, to give you easy access to the nutrient tank. Now that water has been pumping through the system for a while, this is a good time to measure the pH level again. If it's still too high, add some more phosphoric acid. Remember that the water should be kept at roughly 20 degrees Celsius, so in winter you will probably need to put a small thermostatically controlled water heater into the tank.
Plants are pre-prepared by propagating them in a small rockwool block. When the roots are long enough, they are placed into the hole in the centre of a larger rockwool block, which has been soaked in seedling nutrient solution. When the roots are dangling from the bottom of the block, it should be placed into the hole in the Correx lid, with the grooves in the bottom of the block facing the same direction as the flow of the water. Now do the same for the rest of the plants, and you have finished setting up your NFT hydroponic garden. For more information about the lights to use with this system, watch the film ‘Guide To Hydroponic Lights'.