Among the various hydroponic growing systems, the NFT (Nutrient Film Technique) method remains a firm favourite, especially with beginner growers. Let’s take a look at this popular hydroponic system and the advantages it offers hydroponic growers.
NFT systems are active recovery hydroponic growing systems. Normally, the system incorporates a submersible pump which pumps the nutrient solution to the roots of the plants. The pump is submerged in the reservoir which contains the nutrient solution, and, when activated, delivers the essential nutrient solution; typically through a series of grow tubes which contain the plants allowing the roots to hang down into the solution.
The grow tubes are normally installed at a slight incline so that the nutrient solution flows along the tubes like an extremely shallow stream, or film of liquid nutrients, before returning to the reservoir. This extremely thin film of nutrient solution allows the root bed to develop in the grow tube, a part of which will be above the fluid and therefore, although always moist, is able to deliver a sufficient supply of oxygen to the roots. This process can be continually repeated as and when necessary depending on the nutrient requirements of the plants being grown.
Plants also need oxygen to grow and this is achieved through either capillary bedding or, alternatively, air stones might be used to support the plants. Typically in NFT HYDROPONICS systems, no growing medium is used and the plants are simply supported, with the roots suspended directly in the nutrient solution.
One of the biggest advantages of NFT hydroponic systems is their efficacy. They are extremely efficient growing systems. However, fine tuning an NFT hydroponic system can be challenging for beginner growers. It is also imperative to avoid interruption in the nutrient supply for prolonged periods of time as this can quickly lead to the roots becoming dry, which may cause irreparable damage to the plants.
NFT design considerations
A well designed NFT hydroponic system will take into account critical factors such as the angle of grow tube inclination, length of grow tube, and the nutrient solution flow rate. Getting this right will ensure that the plants enjoy optimal water, nutrient and oxygen supplies. Typically, the slope of grow tubes should be between 1:30 and 1:40 to avoid ‘localized ponding’, and a maximum length of around 12 metres is recommended. Flow rates might vary between 1 litre per minute to 2 litres per minute depending on the particular plants being grown and the stage of their development; typically with slower flow rates immediately after planting.
The main advantage of an NFT hydroponic system is the enhanced growth and yield results from this method of growing. However, one major drawback is its susceptibility to interruptions in the flow of water, and hence, nutrients, in the case of a power outage.