The Nutrient Film Technique Hydroponics System

The Nutrient Film Technique hydroponics system is one of the six main types of hydroponic systems. Sometimes abbreviated to NFT, this system is unique because it requires no growing medium.

This article will describe in some detail what this system is and how it works.

The Nutrient Film Technique derives its name from the very shallow level of water used in its recirculating stream, which is hardly any more depth that a film of water, hence the name. This stream constantly flows over the plants’ roots.

It is only the lower parts of the root system which are submerged in its nourishing nutrient-rich water, while the upper portions of the roots are freely exposed to the air within the growing environment (ideally a grow tent), thereby allowing the root system plenty of oxygen.

Principles of the Nutrient Film Technique Hydroponics System

The NFT system is the only basic type of hydroponic system that relies on this constant flow of nutrient-rich water that feeds the plants, the lower parts of the roots constantly submerged in the nourishing flow.

The Nutrient Film Technique hydroponic system is a simple one to build and maintain; the main thing to get right is the angle of the slope, which causes the flow of water. The result will provide you with a quick growth cycle for your plants and thus a frequent harvest. The NFT system is quite popular among hydroponic growers for all these reasons.

The basis of the NFT system is a very shallow nutrient-rich water solution that is allowed to flow down a gentle slope. Like the Flood & Drain system, the NFT design uses a water pump to ensure the uninterrupted flow of nutrient solution. The difference between this and the Ebb and Flow technique is that the plant roots remain constantly submerged in the nutrient solution; there is no interruption to this.

In this sense, the NFT system provides the optimal conditions for the plants to grow and flourish.

The Nutrient Film Technique Hydroponic System in Detail

In order to build your Nutrient Film Technique system, you’ll need the following:

• A large reservoir for the nutrient-rich water solution
• A pump
• A Channel in which your plants can grow in constant contact with the nutrient solution
• Tube connections from the pump to the plants’ growing tubes
• Containers or pots in which the plants can sit

The two main components are the growing channel and the nutrient solution’s reservoir.

Some descriptions of the NFT system indicate that no growing media is necessary, while others specify that some kind of growing medium is used, such as coco coir, perlite or Rockwool, which will firmly hold in place the plants. Many growers find that they don’t need any growing medium because the roots already have an abundance of nutrients, moisture and oxygen simply because of how the NFT system endows them with these.

Over time, the roots of the plants will grow and form into quite a dense matting at the bottom of the channel; some growers find that a support trellis is needed.

A pump is used to pump the nutrient solution to the beginning (the raised end) of the sloping grow tray, and a recycle pipe or drain pipe or tube is provided at the other (lower) end of the grow tray to return the nutrient solution to the reservoir.

The whole system is in a constant stream all the time, caused by the nutrient solution’s flow by gravity down the grow tray and the pump’s action to force the nutrient solution up again to the start of the grow tray at the upper, slightly raised end.

The nutrient pump is sometimes submerged in the reservoir, while in most configurations, growers use an air pump outside of the reservoir that feeds air into an air stone submerged in the reservoir.

As they are constantly submerged in the flowing nutrient solution, the roots of the plants are continuously nourished. The thinness of the ‘film’ of the nutrient solution ensures that the plants are not overly soaked by the water but are optimally nourished; this thin quality also means that the upper areas of the root system are always dry and take oxygen from the air.

What Are the Best Plants to Grow in a Nutrient Film Technique Hydroponic System?

Quick-growing plants such as herbs and lettuce are ideally suited for this system. Greens and strawberries can also be grown using the NFT system commercially.

Some growers find that they will require some form of trellis to provide support if they seek to grow heavier plants such as tomatoes. The Nutrient Film Technique system is not the best choice if you want to grow heavier types of plants needing greater support as the thin film, by definition, is not built to support or sustain heavier plants.

The Grow Tray in Your NFT System

The nutrient solution should pass through and among the roots as uniformly as possible, so the grow tray must be angled downward slightly to enable the nutrient solution to flow down due to gravity.

Material such as PVC piping or a round plastic tube is ideal for the grow tray. There should be holes drilled along the length of the grow tray piping in which to fit the pots or seedlings. All these materials are easy to work with and inexpensive to buy.

One aspect of tubular design carries a problem: the ‘film’ of the nutrient solution will not uniformly flow among the roots because the roots in the centre will have a greater depth than the roots at the edges. For this reason, it’s best to use a flat-bottomed grow tray.

How Do You Place Seedlings in an NFT Grow Tray?

When faced with planting seedlings in your NFT hydroponic system’s grow tray, there are two recommended ways; your personal preference or your own experience and observation will determine which method you should use.

One choice would be to put your seedlings right into the holes drilled into the PVC grow tray.

The other is to place your seedlings inside net pots, which will provide more stability, and then put these pots into the drilled holes.

As many growers prefer not to use any growing media, the first option is preferred by these growers; in fact, this is the option chosen by most people.

Whichever one you opt for, always check the plants’ roots regularly and trim them before they have a chance to grow long enough to potentially clog up your system.

As to the length of your grow tray, a shorter tray will, at least partially, get rid of the problem of the oxygen and nutrient contents decreasing as they pass along the tray, meaning that the plants at the lower end of the tray will not get the benefit of the same amount of these as the plants at the upper end (the beginning at the top of the slope).

You’ll be able to check whether this effect occurs over time, as the plants at the lower end of the tray will tend to be smaller than the plants at the upper end. If this is the case, switch to a shorter grow tray.

The Reservoir in Your NFT System

The reservoir is the ‘home’ of the nutrient solution. The solution is pumped into the grow tray at the upper end of the tray, where it flows by gravity and is returned to the reservoir by the return pipe at the lower end of the tray.

An air stone should preferably be used at the bottom of the reservoir, which is connected to an air pump situated outside the reservoir. This arrangement serves to further supply oxygen to the water.
The size of the reservoir in your NFT system is determined by the number of plants you wish to grow in the system.
Should you want as many as 50 plants of about the same size as lettuce, you should get a reservoir with a capacity of five gallons as an absolute minimum. For every additional 20 plants or so, count on adding another gallon to the size of your reservoir.

Where you place your NFT system is something you should think about before you start building it; the reservoir will be the largest and heaviest component of your NFT system. It should occupy a very secure space, stable and well-supported.

As your Nutrient Flow Technique system is constantly running, you will not need a timer like other hydroponic systems. Power outages will cause the system to stop working altogether, so ensure that your pump is in good working order and preferably have an alternative power supply in the event of any loss of mains electricity.

For any grower who chooses to have an NFT system, it is recommended to have a standby battery-powered source in cases where the normal electrical supply is cut, for whatever reason. You can also buy an automated unit that ensures the battery backup kicks in when the system is unattended (during the night when you are asleep, for example), ensuring that the system will constantly run uninterrupted.

Advantages of the Nutrient Film Technique Hydroponics System

There are several advantages to choosing to have a Nutrient Film Technique hydroponics system, and they are as follows:

• Easy to build and easy to maintain
• Can function without any growing medium, so choosing one growing medium over any other option is not necessary; also less expensive because of not having to pay for this
• The absence of a growing medium will generally mean less chance of pests (due to the pests’ tendency to favour growing media in which to live and breed)
• NFT systems do not need much water to function perfectly well
• Steady and uniform pH is maintained easily because of the continuous flow of nutrient solution, which tends not to allow a buildup of salts to occur
• Should it be necessary, it is quite easy to disinfect the whole system and the plant roots

Disadvantages of the Nutrient Film Technique Hydroponics System

There are several disadvantages to opting for an NFT hydroponics system, and these may be summarised as follows:

• Channels could become blocked if the roots are not trimmed back regularly or properly
• Due to power outages, if the flow stops, then the plant roots could dry out quite rapidly
• Power outages, or pump failure due to any cause, could mean that your plants could die, especially during the warmer months
• The channels could heat up due to intense and direct sunlight faster than the roots’ system areas
• Saline water isn’t a good choice for your NFT system as the salt levels within the system will, over time, decrease
• NFT systems are not suitable for larger plants that need greater support, even if a trellis system is used.
• The NFT system is not suitable for any plants with large or long root systems (for example, carrots)

To conclude, the Nutrient Film Technique hydroponic system is relatively easy to build and maintain. It is a setup that allows a short growth cycle and gives you your first harvest relatively quickly.

The NFT system is good for growing herbs of all sorts, most lettuces, kale and small greens.

This is an excellent all-around choice for the beginner to hydroponics which will provide you with very little work and reward you with a good harvest in double-quick time.