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Hydroponic Systems Part 2 – NFT Nutrient Film Technique

This system is probably the simplest of all hydroponic systems. It does not involve the use of timers to turn the pumps off and on. Seeds should first be propagated in a separate tray until they have a good enough root base to place in the system.

How does it work?

The kit consists of long, shallow trays that come with a long lid that keeps the system closed. There are cutouts in the lid which is where the plants are placed. The plant sits in a plastic pot with slits to allow roots to grow through. They look like a smaller version of the inner pot used in flood and drain systems.

The trays are placed over a water tank and a pump attached to one end to pump water into the trays. There should be a good slope in the trays so that the water flows down the tray and back into the water tank. Usually the gradients used are 1:30 or 1:40, this prevents water from pooling in depressions caused by uneven surfaces and roots. The idea is that plant roots are continually bathed in a nutrient-rich supply of water and produce healthy, linear-growing plants.

The name nutrient film refers to the thin root film that will eventually form on the bottom of the tray. It should be a very shallow stream of water with only the base of the roots submerged; this allows the rest of the root to be open to air and get the oxygen needed for growth.

Systems come in different lengths that can hold different amounts of plants. Essentially you can have any length of NFT system, however the longer the system, the more chance there is of flow disruption. Systems longer than 12 meters tend to have less plant growth towards the end because the nutrients in the water are taken up by the plants closest to the reservoir. However, this problem can be overcome by installing another water supply along the channel.

Issues

I’ve mentioned a couple of issues with NFT systems, such as water pooling and reduced nutrients in the water in long system setups. However, there are a couple more.

pump failure

As NFT systems only require a small and shallow water supply, the pumps used are not very powerful. They are also on all the time, which means they get a lot of action over the course of the grow. This, along with possible salt precipitation from dissolved nutrients (especially in hard water areas), means that at some point the pump is likely to fail. If you can catch this quickly, apart from the cost of a new pump, there is no real problem for the plants. However, if this goes unnoticed, it means that the roots will dry out very quickly and this will affect growth.

illness

Plant roots are constantly submerged in water and this can lead to bacterial infections such as pituitary. Pythuim is best known as root rot and can decimate your crops if not caught early. There are products on the market that can eradicate this if you’re unlucky enough to get it, but the best way is prevention. This can be accomplished by changing the water reservoir periodically and adding preventative additives to the nutrient solution.

Stability

Plants that produce a lot of fruit can become unstable in an NFT system. This is because the roots grow long and flat and don’t have much stickiness. This makes the plant heavy and they fall off the trays, not ideal! This can be overcome by supporting the plants with yo-yos, ropes or poles. This will give the plant some stability and allow it to continue to grow and bear fruit without tipping over.

Summary

Even with the problems mentioned above, these systems are a great way to demonstrate the use of hydroponics. They are an excellent and inexpensive system to use as an introduction to growing your own produce at home.

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