The Ultimate Guide to NFT (Nutrient Film Technique) Hydroponics

While there are a variety of different methods of growing plants hydroponically, NFT is the only one which requires a constant flow of liquid in order to feed the plants, with the roots of the plants hanging down into the stream as if they were dipping their toes in a stream as it flows by.

This may sound fancy, but actually it is not a particularly difficult hydroponic system to put into practice, and after learning a few basic principles NFT hydroponics is relatively simple to set up and to maintain.

Accordingly this guide should prove just as useful to hydroponics beginners just as much as to those experienced already in other hydroponic systems.

How does NFT Hydroponics work?

Nutrient Film Technique Hydroponics is a method of cultivating plants without soil; a nutrient solution which constantly flows through the plants’ dangling roots is able to provide all of the water, nutrients, and oxygen that the plants need for both a healthy and rapid growth.

This also means that the upper part of the roots are exposed to more oxygen, which allows the plants to grow faster (this is actually the basic principle behind all types of hydroponics).

Because plants roots use oxygen to absorb nutrients, the more oxygen they get the more nutrients they can absorb and can accordingly grow much faster.

How is an NFT Hydroponics System Set Up?

This technique uses a chamber set at a slight incline (to let the nutrient solution continue flowing) for the roots to grow in.

Normally these setups will have multiple chambers since there is a limit to how many plants you can cram into the same chamber before all the nutrients get sucked up before reaching the plants at the far end.

The plants are set into holes in the top of these growing chambers so that the roots dangle down into the flow of nutrient solution.

All you really need to support the plants in the top of the chamber are some net pots.

Your nutrient solution will be pumped from a reservoir into the more elevated side of the growing channel, and then once it has flowed through the channel it ends up back in the reservoir again.

This ensures that you don’t lose any leftover nutrients and also helps to reduce water consumption.

Why choose NFT over another hydroponic system?

The major advantages of NFT over other methods are as follows:

  1. Conserves both water and nutrients
  2. No need to bother with timers or watering cycles
  3. Less concern about aeration since the circulation of the nutrient solution is constant
  4. Doesn’t require a growing medium
  5. Is relatively inexpensive to set up
  6. Adapts easily to various spaces and plant requirements
  7. Relatively easy to build and to maintain

Are there any disadvantages to NFT hydroponics?

There are a few for certain.

For one, an NFT system will depend on electricity 24/7 in order to run the pump, and any problems like a power outage or a pump failure could lead to significant damage to the plants as it won’t take long for them to dry out without any damp soil to rest in.

Another disadvantage is that NFT systems don’t work well with larger, fruit-bearing plants since their root systems will get pretty large and wild before it’s time to harvest and can clog up or block your flow of nutrient solution.

NFT really only works well with fast-growing plants like herbs, lettuce, or other leafy greens that can be harvested before their root systems get really out of whack.

DIY building guide for NFT hydroponic systems

The materials you are going to need are as follows:

  1. Some tubing
  2. A submersible pump
  3. A reservoir for the nutrient solution
  4. Small baskets to hold up the plants
  5. Growing channels

Growing Channels

First of all, what to use for your growing channels. Although some people use PVC pipes with success, they are actually not ideal since they provide little room for oxygen.

A chamber with a flat bottom is much more ideal to give the roots more room the breathe. It will also be ideal to use something with a removable top to make it easier to monitor your plants regularly.

As for the length of your growing chambers, in general they should not be longer than 40 feet or 12 meters.

Any longer than this and it is more than likely that your plants at the far end of the channel are not going to be getting enough nutrients by the time the solution makes its way to the end.

This limitation is in many cases not a problem, since shorter channels allow you to make use of your available space more efficiently in any case.

Baskets

Your baskets, aka net pots or net cups, are used to hold your plants up above the growing channel and to let the roots dangle down inside of it.

You will likely want to get variously sized baskets (as well as growing chambers with variously sized holes) in order to transfer plants as they grow larger.

Reservoir

Just like with any other hydroponic system, it is recommended to get a reservoir made from an opaque material, as this helps to prevent the growth of algae as well as bacteria.

If you set your reservoir up at the low point of your circular system, then there shouldn’t be any need for an additional air pump or air stone to aerate your nutrient solution as the solution will get continually re-aerated as it cascades from the return line.

Keep in mind that you’ll have to monitor the level of the solution in the reservoir, and also the pH and nutrient levels of the solution so you can make adjustments as needed.

Submersible Pump

It will be important to get a reliable pump, since as mentioned above any interruption in the flow of solution will lead to the plants drying out quite quickly.

This does not mean that you need a high-powered pump, since actually what you want in this system is only a thin layer of liquid running at all times, and because the way the system is set up lets gravity do a lot of the work.

It is also ideal to get a pump with an adjustable flow rate so you can modify your system easily as your plants get larger.

Tubing

This is more or less a no brainer since you’re going to need however much is required to get your nutrient solution up to the high end of your growing channels, and then enough to get it back down into the reservoir again.

Flow Rate And Channel Slope

Ideally you want to have a fairly shallow stream of nutrient solution running past at all times, which generally means you should aim for a flow rate of about 1 liter per minute (although anywhere from 0.5 to 2 liters can be made to work as well).

The ideal slope for your growing channels, in order to achieve this range of flow rates, is between 1:30 and 1:40 (this means that for every 1 cm difference in height, you should have 30-40 inches of length).

As you become more expert at using these systems, you will find that you will want to modify your flow rate and incline as your plants change in size.

For this reason, it is ideal to design a set up that allows you to adjust the slope of your growing channels without too much trouble, as well as to buy a pump with an adjustable flow rate.

Starting Plants In An NFT System

Some people transplant their plants from a nursery once they have rooted, but it is possible to start your plants off in your NFT system from day one.

It does make things more complicated, but you can save yourself a significant amount of time by using this method. You will need a growing medium in your baskets for your seeds or cuttings (something like perlite, coco coir chips, or oasis cubes that won’t get waterlogged).

In order to encourage rooting, you should raise the volume of the solution running through your channels while at the same time lowering the speed of the flow. Just don’t raise the water level too high or there won’t be enough room for oxygen inside the channel.

You will also likely need an air pump or air stone in order to increase the aeration of the liquid in the reservoir. Although this may sound much more complicated then simply allowing the seeds to sprout in a nursery beforehand, if you have a professional operation running you will also find that seeds will sprout and develop much faster using this method than they will growing in soil, so if you can master this method you may eventually be able to save a very significant and also valuable amount of time.

Hopefully this basic outline has been enough to explain what an NFT hydroponic system is, as well as give you a basic idea of what materials and what kinds of maintenance will be needed in order to get a system like this up and running.