The NFT (Nutrient Film Technique) used to be commonly used among commercial and smaller scale hobbyist or amateur hydroponic growers. Its use has diminished among commercial growers in recent years mainly because new hydroponic techniques exist today that are better suited to large-scale farming.
Amateur hydroponic growers however still use NFT often. It's not that expensive, it's very easy to use, and it can be easily adapted to suit many different plant types.
The NFT is one kind of solution culture in hydroponics. Solution culture hydroponics involves the growing of plants without growth medium and without soil. Many hydroponics growers believe that solution cultures are the only true form of hydroponics. They say that when growers add solid growth mediums, they are adding nutrients to the plants in the same way soil does. NFT on the other hand, treats the plants only with nutrient solutions prepared by the growers and delivered to the plants root system via water.
NFT Hydroponics Systems work by generating a constant water flow at the plants' root systems which are suspended in a tub. The slow moving water solution is spread out across a flat surface at a depth of approximately 1 to 3 inches. This shallow solution depth is constantly maintained to create a nutrient film over the plant roots.
When setting up your own NFT system you will need a shallow, flat-bottomed tub and a submersion pump which will keep the water flowing over the plant roots. The plants should be placed close together in order to enable the nutrients to more readily cling to the roots. The submersion pump will constantly recycle the water back into the system. And because the water is being constantly recycled, you will need to closely monitor the nutrient levels in the water.
The NFT technique does have a few potential drawbacks which need to be addressed. For example the nutrients necessary for the plants can cause damage to the submersion pump. If the submersion pump fails, or if there is an electrical failure, your plants will not be getting the nutrients they need to survive. A relatively short disruption in the pump can lead to complete failure in your plants.
Nevertheless the NFT Hydroponic System remains a viable method of hydroponic gardening for small scale and indoor gardeners. By closely monitoring the pump and nutrient solution, hydroponic gardening can be made nearly risk free and quite productive!