Nutrient film technique is a Continuous-flow solution culture. A very shallow stream of nutrient solution is recirculated in a thin layer past a bare root mat of plants in a watertight channel, with an upper surface exposed to air. Unlike with deep water culture hydroponics, a stream (or “film”) of nutrient solution flows over the ends of their roots.
The most common setup involves rain gutter pipes with holes to place the netcups with plants. The pipes are laid down at an angle, and nutrient solution is pumped to each pipe from a reservoir. It is recommended that slopes of 1:30 to 1:40 be used and flow rates for each gully should be 1 liter per minute. To prevent ponding in in locally depressed areas, channel length should not exceed 10–15 meters.
Developed in the 1960s by Dr. Allen Cooper, the NFT hydroponic system is mostly used for leafy greens like lettuce.
Commercial hydroponic NFT growing systems
Green Automation’s shows us an automated growing system optimized for head lettuce production. The system is designed for growing head lettuces and herbs that are sold with their root ball (living lettuce) in a pot or as cut head lettuce.
HolaFresh was established in Australia in 1991 and has an impressive range of herbs grown using the NFT hydroponic system: Baby Spinach Basil Bay Leaves Chives Continental Parsley Coriander Curry Leaves Dill Kaffir Lime Leaves Lemongrass Lemon Thyme Marjoram Mint Oregano Parsley Rocket Rosemary Sage Tarragon Thyme Watercress
Hoocho explains how to build an outside NFT hydroponic system using plastic pipes: what you’ll need, reforming the PVC ends, drilling holes, slope, running irrigation lines, irrigation flow rates.
If you want to build an indoor NFT system you can make a space limited one, where the the pipes are placed above the nutrient reservoir:
An even more space efficient NFT hydroponic system would be to place the PVC pipes on shelves and make a vertical hydroponic system
Nutrient film hydroponic advantages
- one of the main advantages of NFT systems is that they require relatively little water, as the nutrient solution is constantly recirculated and only a small amount of water is lost through evaporation and transpiration.
- less prone to root rot as the roots are not submerged into water
Nutrient film hydroponic disadvantages
- it takes more space than a deep water culture hydroponic system as you need to lay down pipes in an angle
- Risk of drying out: Because the roots of the plants are suspended in the air and not submerged in water, they can dry out quickly if you have a failing pump
- doesn’t work well for plants with big roots or plants that need a lot of support
CropKing NFT 4-6 Hydroponic Leafy Greens Growing
The CropKing NFT 4-6 is an introductory system designed to ease growers into using the nutrient film technique to grow hydroponic plants. Suitable for leafy crops such as lettuce and herbs, this systems arrives with everything you need to get started, except a reservoir.
NFT hydroponic system maintenance
Maintenance for a NFT system is mostly about checking the nutrient solution and cleaning algae and overgrown roots that might block the water channels.