NFT – ingenious, an amazing combination of ‘can’t go wrong’ simplicity and stunning results. Typically produces 3 to 4x as much yield as traditional soil growing. NFT systems constantly pump a shallow film of nutrient solution over the roots and back into the reservoir, because the feeding is constant and whatever the plants don’t use drains-off - over and under-watering are impossible. What’s more, very little growing medium is used so the plants have constant access to oxygen.
In closed cultivation systems including pot cultivation and passive hydroponics the grower has to decide what quantity of water and nutrient and in what ratio plants should be fed. This is difficult and even the most experienced growers make big mistakes.
Active Hydroponics is open cultivation. The plant is automatically provided with water and nutrients and simply takes what it needs from what is supplied. Whatever the plant doesn’t need drains away or into a reservoir to be reused. This prevents over or under-watering or feeding.
There are simple rules to follow regarding the make-up of the nutrient solution and all you need is reliable kit. Plants grown in active hydroponic systems develop strong healthy roots, have easy access to oxygen, water and nutrient, and overfeeding and underfeeding is prevented.
Greater take up of water and nutrients – Because plants in NFT have constant access to nutrient solution they take up much more water and nutrients than plants fed a few times per day. The more water and nutrients a plant can take-up the better the yield it will produce. Never underfed or under-watered – plants are never waiting for you to feed or water them. This means that the plants are productive (growing) all the time.
Unrestricted access to oxygen – in NFT there is very little medium so the roots always have access to oxygen, essential for fast growth.
over-watering – any water not needed by the plant drains away. So there’s no water-logging so no restriction of the plant’s access to oxygen.
No nutrient build-up – any nutrients not needed drain back into the tank, so there’s no build-up of potentially damaging nutrient salts.
Reduced chance of disease – There’s no soil in NFT so you won’t have to worry about soil-borne diseases.
Once set-up all you do is keep the tank topped-up with nutrient solution, empty and refill the tank approximately every fortnight and keep an eye on pH levels, adding PH down as required.
Click these links to see setting up of the Growtank and auto top-up systems.
The first NFT (Nutrient Flow Technique) systems were introduced in the seventies. Allen Cooper developed the first NFT system in England. In NFT systems a series of tubes provide a constant, gentle flow of nutrient solution to the roots. The nutrient solution that drains from the root environment is gathered in a reservoir and then recirculated to the plants. In recent times, the NFT tables have also become very popular for cultivation in this manner. This approach works on the same principle as the first tube system developed. To ensure that the nutrient solution has sufficient flow the tubing itself must have a fall of around 1%. In a tunnel construction the flow rate should be around 1litre per minute. Take care to ensure that the root mass at the bottom of the tunnel doesn’t become too dense! If this occurs there is the danger that the nutrient solution will flow over the outer layer of roots, so that there is not enough contact between the nutrient solution and the roots inside the root mass. Under these circumstances the plants will wilt more quickly and nutrient deficiencies may arise. In order to prevent such a thick root mass from developing it is advisable to make sure that the tubes are no more than 9 meters in length and that they have a diameter of at least 30cm. An imminent nutrient deficiency in a NFT system can often first be seen on the plants at the end of the flow (the lowest plants). This is because the plants at the beginning and middle of the flow are still able to extract nutrition from the nutrient solution. By keeping an extra close eye on these plants, nutrient shortages can be spotted and corrected, sooner. Correction is achieved by increasing the flow rate and/ or increasing the strength (EC) of the solution. As well as nutrient deficiencies, oxygen shortages are often the first problems seen with the plants at the end of the flow. A shortage of oxygen causes the roots to turn brown with a corresponding drop in the plants uptake of water and nutrient. The chances of oxygen shortages arising are greatest during the fruitforming phase and in stressful situations. Using enzymes that stimulate root decomposition leads to fewer dead roots remaining and a more vibrant plant. Under normal circumstances there will always be a certain amount of dead root material in the system, but, so long as there are enough white, healthy roots, this is no reason for panic.