Aquaponics 101 – NFT

NFT? WTF? Since starting with Aquaponics (AP) I have been intrigued by NFT.  While I’ve been fiddling with gravel growbeds the “big boys” have been showing off their NFT systems.  But what is NFT anyway?

Nutrient Film Technique (NFT) was invented in the 1960′s by Dr Allan Cooper at the Glasshouse Crops Research Institute in the U.K.  With the NFT system, a thin film of nutrient solution flows through plastic channels, which contain the plant roots with no solid planting media. The root mat develops partly in the shallow stream of recirculating solution and partly above it.

This is a common method used in Hydroponics, but how do we apply it to Aquaponics?   After some research at Backyard Aquaponics and TCLynx I set out to work, building a small pilot NFT system in my greenhouse.

First I needed a nutrient channel.  I looked around and found a length of 110mm PVC pipe.

pipe1

Then I cut 18 evenly spaced holes in the pipe.

holes

The plants are suspended above the flow of nutrient-rich water so we need to hold them in position.  But how?  Enter the “yogurt cup trick”.  Eat some (lot’s of) yogurt, wash out the little cups well and drill some holes in the bottoms as follows.

holesincups

The idea is that we plant seeds or seedlings in these cups, and then the roots go down through the holes into the water flowing in the nutrient tube.  I just placed a small submersible pump in one of my ponds and pumped water into the pipe.  I used endcaps to seal the ends of the pipe.

But won’t the roots suffer from root rot if continually suspended in water?  Yes they will, but only if there isn’t sufficient oxygen.  So what then is the solution?  Add oxygen directly to the water with airstones.  Here is what the aerated water flowing through the pipe looks like.

bubbles

I have used gravel in the cups to hold the plants in place and a lamp wick through the hole and into the water to draw water up and into the cup.  The beauty of this system is that the plants are so clean and you can lift the cup out of the hole at any time to inspect the plant and it’s roots.

Here is what the end product looks like.  I will post regular photographs as I plant seedlings and slowly tweak (or ditch) the system.

finished1

The possible problems that I can see here, are a build up of solids in the pipe and even possibly a blocking of the pipe by invasive roots.  To prevent this I have only glued on the endcap at the inlet side.  The other endcap can easily be pulled off and the pipe cleaned out.  Also, I am only using plants with small, non-invasive roots like lettuce in this system.

lettuce

Only time will tell.

Synaptoman

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8 Responses

  1. NFT, I like it, can’t wait to see how it works out!

  2. Hey, have you noticed a white fly that seems to come around lettuce? I am wondering if there is any plant around that can also be planted to discourage these flying pests from attacking lettuce?

    Are you familiar?

    • Yep, it’s White Fly. Very common in greenhouses where heat and humidity (or moisture) is high. There are organic solutions that you can try. It isn’t serious but does tend to weaken the plant. Very common on tomatoes. Plant mint but be very careful that it doesn’t take over (and it will).

  3. Thanks so much!!

    What are you thoughts on planting marigold to help as a deter them?

  4. [...] Aquaculture Manuals ← Aquaponics 101 – NFT [...]

  5. [...] to Nutrient Film Technique DWC does not have enough grow media to support large plants or root plants. Since this will be an [...]

  6. How many fish do you have supplying the nutrients to the nft system? I have had great success growing vegetation by using chemicals. I would like to utilize fish to replace my chemical nutrients, but I am struggling to find how many fish I will need.
    One last idea, why did you flood your nft pipe?
    Nutrient Film Technique is supposed to be only a shallow stream of water, or a “film” on the bottom of the pipe. When you reduce your water level in the pipe to a shallow stream air can then fill the void left behind eliminating the need to aerate the pipe.
    Cool looking system and thanks for letting us all in on your experiment!

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