The nutrient film technique is a recirculating hydroponic system in which plants sit in channels (gullies) set at a slight slope. A pump delivers solution to the high end, a shallow film flows past the roots and drains back to a reservoir. Roots form a mat on the channel floor, wetted below and in air above.
In practice
NFT is the standard for lettuce and herbs and is used for tomatoes commercially, but it is less forgiving with cannabis. A large cannabis root mass can dam the channel, and if the pump stops, the thin film offers almost no buffer, so roots can dry within minutes. Growers who use it run wider channels, steeper slopes, short runs and backup power or alarms. Typical slopes in vegetable NFT are around 1:30 to 1:100being reviewed.
Don't confuse with
- Ebb and flow: floods and drains periodically rather than flowing continuously.
- DWC: roots fully submerged in deep, aerated solution.
A recirculating (closed) system returns drained nutrient solution to the reservoir to be reused, saving water and nutrients but needing more monitoring and sanitation.Runoff is the water or nutrient solution that drains out of the bottom of a container after irrigation; growers test it to see what is happening in the root zone.Ebb and flow (flood and drain) periodically floods a tray of potted plants with nutrient solution, then drains it back to a reservoir, pulling fresh air into the medium.DWC (deep water culture) suspends a plant's roots in an aerated nutrient solution, typically in a bucket with a net pot lid and an air stone.A reservoir is the tank that holds a system's water or nutrient solution, the place where pH, EC, temperature and oxygen are measured and adjusted.The root zone is the volume of medium or solution where a plant's roots live, including its water, air, temperature, pH, EC and microbes.
