The nutrient film technique, NFT for short, is a hydroponic technique in which the plants stand in a shallow stream of water containing all the dissolved nutrients necessary for plant growth. This water flow is circulated through growth tanks containing the roots of the plants. The plants absorb the nutrients through the roots, and because the stream is shallow and the roots are also suspended in the air, the roots can also absorb oxygen.
In an NFT system as in many other hydroponic systems there are essentially 2 components: the nutrient solution and the grow trays. The functioning follows the following principle:
- A reservoir contains the nutrient solution.
- A pump circulates the water from the reservoir through the growth tanks.
- The grow trays contain the plants. The plants grow in a growth medium and are in containers with slots, so-called netcups.
- The netcups allow the roots of the plants to hang in the water flow and thus absorb the nutrients.
- After the nutrient solution has flowed past the roots, it returns to the reservoir via a hose.
The reservoir contains the necessary nutrients for the plants. The circulation of the solution also brings oxygen into the solution, which is good for the root health of the plants. The grow trays should normally be inclined so that the water can flow well.
The plants themselves should be kept in air and water permeable containers (usually netcups) so that the roots from the pot can reach the water and thus air can reach the roots.
An NFT system is basically also well suited for vertical farming, as several growth trays can be mounted one above the other without any problems. The water can circulate through several levels and each plant takes out the necessary nutrients.
NFT is more suitable for smaller plants, because often only little growth medium is used and the netting pots are only hanging in the growth trays, there is often little support. Larger plants such as tomatoes, cucumbers, pumpkins, however, need a lot of hold because the fruits are correspondingly heavy. Of course, to remedy this situation, you can also provide some tools for plants to give them the necessary support.
The main advantage of NFT, is its simplicity and environmental friendliness. This system is well suited for beginners, as the system is easy to control and in case of a problem, it is possible to quickly diagnose where the fault lies.
- Little growth medium is needed.
- Low water and nutrient consumption.
- Easy to check the health of the plants, as roots are easily accessible.
- Few salt deposits, as water is in motion.
- Easily scalable by many more growth trays
- Environmentally friendly, as no groundwater can be contaminated
- Very easy to build
The disadvantage of NFT is that it is not suitable for all plants and small technical faults such as a broken pump or blocked drainage pipes can quickly turn into big problems.
- Water must circulate permanently
- Small technical errors can have devastating consequences
- Sufficient support and stability must be provided for large and heavy plants
- Direct and high levels of sunlight can heat up the growing containers and damage the roots
- The drain can be blocked by roots
In principle all plants are suitable for an NFT system. As already described, for larger plants you have to take certain stabilizing precautions so that they have enough hold. In addition, you should avoid plants such as carrots or turnips, as these have taproots and there is usually no room for them in the growth container. Apart from that, it is as always important that all plants in the system grow in the same pH-value range and that the nutrients are correct. To plan more accurately which plants fit into a system, we recommend our Hydroplanner which supports precise planning of a system and indicates the resulting pH and TDS ranges.
With a normal NFT system, the water has to circulate constantly so that the plants are not undersupplied, or even burn. This causes the following problems:
- The water could overflow if the roots of the plants block the drain
- There is a high energy demand, depending on the size of the system
To prevent these problems, the NFT system can be easily modified by taking the slope out of the pipes and regularly flooding the pipes with water. It is now important that the drain hose is not flat with the bottom of the growth bowl, but sticks out a bit, so that the water stays in the tube. The water should not be left standing too long, because otherwise no new oxygen can enter the system. It is no longer necessary to maintain a permanent flow of water through the growth tanks, but you should still circulate the water at regular intervals to enrich the solution with oxygen.
if you want to learn more about a nft system and maybe want to start building your own, we created a simple DYI Guide for you to become a hydroponics farmer yourself.