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How Does Nutrient Film Technique work?

When people think of hydroponics they often think of NFT, but don’t always know what it is.

In this article we’ll explore what Nutrient Film Technique (NFT) is, how it works and why it’s known as one of the simplest growing methods around.

What is Nutrient Film Technique?

Nutrient Film Technique or NFT as it is more commonly known is where a shallow stream of nutrient solution flows, like a film over the plants roots. The nutrient solution is pumped from a vessel, like a reservoir tank over the plants’ roots, where it is recirculated through the NFT system again and again. Making it one of the most efficient hydro systems available.

How does the NFT system work?

The constant flow of nutrient solution flows over the plants’ roots so that it can feed when it needs, rather than when someone is able to water their plants. A tray or reservoir sits below a tray, which is sloped to allow the nutrient solution to easily pass over the roots of a plant and then back into the reservoir. The nutrient solution rises from the reservoir onto the tray above via a pump, which send the nutrient solution from the reservoir up onto the top tray.



Growing medium isn’t required in an NFT system, though the plants are often held in place with an inert media, like a rockwool cube, like a Grodan block. That’s not to say you can’t use other types of media in an NFT system.


A quality propagator provides the best environment for healthy seeds. An X-Stream Heat propagator allows you to control the heat and humidity to achieve a well rooted plant that you can then transplant to a hydro system.

Using Compost

One way of generating high quality plants to be put into an NFT system is to germinate seeds in a seed tray of compost. When they’re big enough you can then transplant them into a plastic pot with drainage holes. Plants are ready to be transplanted when you can remove the pot and the compost remains bound by the white roots of your transplants. 

When to Plant Out

One of the most important things to remember is that you should not transplant into an NFT system until the plant is well rooted. It’s important that there’s a lot of white roots available to take the nutrients that are circulating throughout the NFT system. If white roots aren’t on the outside they’re likely to become saturated with no access to oxygen and ultimately die-back.

Using Rockwool

Before using rockwool, like a Grodan block, it is highly recommended that you soak the rockwool overnight in water at pH 5.5. What this does is reduce alkalinity. You can then plant seeds in the rockwool cube. When doing this gently bury and cover over the seed using a blunt instrument and allow to germinate.

Cuttings Developed in Aeroponic Propagators

Bring the seeds or cuttings on as directed by your propagator instructions.

Young plants can then either be transplanted to an alternative medium, e.g. rockwool, and grown on before transplanting to your system, or grown on in the propagator until the roots reach 8 – 10cm in length and transplanted directly into your NFT system.

Raising Transplants from Cuttings

Follow the instructions for raising from seed but DO NOT use nutrients in the water until your cutting has rooted.

Before Planting Out

Add nutrients according to the manufacturer’s instructions. Check pH.

When To Plant Out

Do not plant into your NFT system until the plant is well rooted. If white roots aren’t on the outside of the growing medium when you place your plant into the NFT system the roots will become saturated with no access to oxygen and will die-back.


Maintaining pH is a key element of using and maintaining an NFT system. Follow these points below and you’ll be on your way to a great grow.

  • Check pH levels in your tank weekly
  • Decide the pH you want to maintain, between 5.8 – 6.5 is ideal
  • Test the pH of the nutrient solution in your tank using a test kit or pH pen
  • If the pH of the solution is in the correct range 5.8 – 6.5 do nothing
  • If the pH of the solution is above the correct range add phosphoric acid (pH Down)
  • If the pH is below the correct range add potassium hydroxide (pH Up)

Use the pH Down or pH Up very sparingly. Adjust pH to your chosen level over several days.

Safety First

Phosphoric acid is strongly acidic and potassium hydroxide is strongly alkaline.
Always follow the safety instructions on the container.

Top Tip

Remember a consistent temperature is key. Use a submersible heater to assist in achieving this.
So that’s what NFT (Nutrient Film Technique) is, how and when o plnt out and what growing mediums

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