About NFT

Various details of system design pH Chart

NFT is an ultra-resource efficient method of growing plants by providing a highly oxygenated, slowly moving film (stream) of dissolved minerals to the roots in a flat bottomed, gently sloped channel (the gully). Plants are placed at intervals along the gully and grown with their root ends constantly moistened by the nutrient film. The nutrient film is shallow enough for most of the root mass to have direct access to oxygen from the surrounding air. The nutrient solution is recirculated through a reservoir that is highly aerated and continuously monitored for pH and nutrient strength. Nutrient strength and pH are adjusted on demand with the use of automated monitor/dosing computer equipment. This provides constant balance and optimum conditions for thriving plant growth. This monitoring equipment is available from Stockers. Dr Allen Cooper in England originally developed the NFT growing method in the late 1970's. It has been commercially feasible for fancy lettuce in New Zealand since the late 1970's. Typical NFT lettuce operations achieve 9-12 harvests a year from the system which produces:

Various details of system design pH Chart Various details of system design pH Chart

Critical Principals of Design

CF Values Diagram of typical nutrient management system

There are a few critical aspects of NFT system design that cannot be ignored -

1. Water Quality
   Source water quality must be a constant. Before even considering hydroponics water must be analyzed beforehand to determine the quality.
   Upon analysis water must be as pure as possible going in. If too many mineral elements are present, i.e. high sodium, heavy metals or pathogens, it must be treated with Reverse Osmosis Membranes and/or Ozone.
   If source water mineral, such as sodium, is too high, reservoir will need to be dumped much more frequently.
   
2. Gully Features
   Gully must be flat bottomed to achieve a broad nutrient film (stream).
   Slope must be a minimum of 1 in 40.
   1 litre a minute flow rate.
   
3. Reservoir Features
   Reservoir should be sized so that when the system turns off the reservoir needs to be able to hold what is out in the system.
   Returning nutrient must fall into the reservoir. All reservoirs must be equipped with venturis for oxygenation. A venturi that operates off pump pressure creates a spa like effect in the reservoir, agitating ethylene out of the solution and introducing oxygen into the solution.