NFT stands for nutrient film technique. It is probably the most popular method of hydroponic growing. Its popularity is thanks to its combination of ‘can’t go wrong’ simplicity and great results. NFT grown plants typically produce 3 to 4x greater yield than those grown in soil.
In NFT nutrients are added to water and this solution is contained in a tank. Plants sit on a grow tray above the tank and the nutrient solution is pumped up to the grow tray and constantly flows over the roots of your plants, constantly giving your plants the nutrients they need.
Whatever the plants don’t need drains into a tank ready to be passed over the roots again.
The nutrient solution flows over the roots as a thin ‘film’ at only 1-3mm deep. The flow is quite slow, just fast enough so that the water is in constant motion.
The only growing medium used is the rockwool that you started the plant in.