Managing Production in an NFT System

How NFT works

In NFT (Nutrient Film Technique) a shallow stream of nutrient solution flows continuously along the floor of sloped channels. The plant sits in a net pot or collar positioned above the channel; roots grow down into the film. The lower surface of the root mass stays moist and absorbs nutrients; the upper surface is exposed to air and maintains high oxygen levels.

Solution flows by gravity along the channel slope, collects in a reservoir at the lower end, is pumped back to the inlet, and recirculates continuously. The system uses relatively little water — the thin film means only a small volume is in circulation at any time — but that volume must keep moving.

Channel design

Material

PVC, polypropylene or galvanised metal channels are all used. The internal surface should be smooth — irregular surfaces cause pooling and anaerobic zones. Channels are typically covered or opaque to prevent algae growth.

Slope

Standard slope is 1:30 to 1:40. On a practical level, check the outlet: solution should emerge in a steady stream, not a trickle or a flood. Adjust the inlet end height in small increments until the flow looks right across the full channel length.

Length

Commercial NFT channels run to 8-15 metres. Beyond that, nutrients at the inlet are progressively depleted before reaching the far end. If the system requires longer runs, a mid-point injection of fresh solution into the channel can compensate.

What to monitor every day

• Flow at each channel outlet: Missing flow from one channel means a blocked inlet or a failed emitter — find it and fix it before the session ends.
• Reservoir EC and pH: Both drift. EC rises as water evaporates and nutrients are consumed at different rates; pH shifts as fertilizer reactions proceed. Measure and adjust daily at minimum.
• Root colour and density: Browning tips or slimy root surfaces are early indicators of a pathogen problem or oxygen deficiency before visible symptoms appear on the shoot.

Crop rotation and hygiene

At the end of every crop cycle, drain the reservoir completely, flush and disinfect the channels, and replace the pump filter. Root debris in the system becomes an inoculum reservoir for the following crop. NFT’s greatest operational risk is not pump failure — it is a pathogen introduced on transplants or surviving in inadequately cleaned channels.