Nutrient Film Technique (NFT) is another hydroponic technique popular among marijuana growers. There is a very shallow stream of water that contains all the nutrients essential for the growth of your marijuana plants. This stream of water run over the bare roots in a gully or channel. It is called nutrient film because of the very thin (shallow) film of water with dissolved nutrients. Below are some important points when setting up your own NFT system to grow your marijuana plants.
1. The success of the system depends on the correct slope of the channel, the right flow rate of the water and appropriate length of the channel. A deficiency in one of these factors leads to an imbalance in the supply of nutrient resulting in slow growth.
2. A major disadvantage of NFT is the lack of buffering capacity because it has no medium. The roots are in direct contact with the nutrient film. This setup isn’t suited in areas where there are frequent power outages.
3. The gullies or channels must also block light from passing through. If the roots are exposed to light, their growth rate can be affected.
4. As a general rule, the rate of flow of the nutrient solution must be around 1 – 2 liters per minute. The slope should be between 1:30 to 1:40. This slope is used to avoid water ponding or pooling of water on the flat surface of the gully.
5. The channel or gully length should be between 10 – 15 meters. Decrease in growth rate is observed beyond this range.
6. The dimensions of the gullies need to take into account the final size of the plants being grown. In the case of marijuana plants, it’s advisable that the width be around 20cm.
7. Before placing the marijuana plants, test the flow of the nutrient solution for a day to find out if there are leaks in the system.
8. The larger the tank used the better. A larger tank minimizes the changes in conductivity and pH of the nutrient solution.
9. The tank should be able to hold all the nutrient solution. During power outages, the roots can be flooded if the tank is unable to hold all the solution. Replace the nutrient solution in the tank every 8 to 10 days.
10. There must be two valves. Valve B is maintained completely open to ensure abundant nutrient supply to the marijuana plants. Valve A is opened just enough to provide the proper flow rate at the ends of the gullies. This will also stir and invigorate the nutrient solution in the tank and sufficiently add oxygen to the mixture.
11. Below is a simple diagram to remind you what the final setup will look like.
NFT has the lowest maintenance cost and there is minimal need for cleaning. With close attention to the setup at the start and achieving the right formula for proper growth, the NFT is a truly a system that produces worthy results with minimal expenses.