Backyard Aquaponics
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This has been getting under my skin for a while now, but it's getting worse.

I'm seeing it all the time now on Aquaponic forums and FB groups, even Youtube vids by Aquaponic or Hydroponic "Gurus" advising people on how to build "NFT" systems. I've seen "backyard retailers" selling these "NFT" systems on Gumtree, eBay etc, and I've even seen retail stores that are supposed to be experts, selling these so called "NFT" systems.

Just this morning I've had two customers in the store and one phone call asking about info on either designing, or getting their already built "NFT" system running properly... that weren't NFT systems.

NFT, or Nutrient Film Technique, uses rectangular cross section PVC channel with a flat bottom, which the pots sit squarely on. The channel is mounted with about a 1 in 40 decline along it's length, with the nutrient solution pumped in the top end and a fine FILM of the solution runs down along the length the channel, contacting the base of the pots along the way, and drains out the low end.

Rant over!...
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Mr Damage - a.k.a: Yabbies
Owner at Perth Aquaponics - Aquaponic Consultant & Trainer
Trade certified Horticulturist & Cert IV TAE

If the round one drains out completely as well what is that called?

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Pete.

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Flood & Drain Pete.

If you maintain a constant water level in the round one, ie: Have the pipe level and pump the water in near the top of the end cap on one end, then have it exit via an overflow at the other end, which determines the max water level in the pipe, then it is Constant Flow/Constant Flood, or possibly even DWC culture, but I'd be more inclined to call it a Constant Flow system.

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Mr Damage - a.k.a: Yabbies
Owner at Perth Aquaponics - Aquaponic Consultant & Trainer
Trade certified Horticulturist & Cert IV TAE

Thank you for the clarification. Where are the roots in a NFT? Also what are the roots in? Media like clay beads or just touching the water?

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Brian's AP
I don't understand all I know about this
Specs: 2600 gallon (347.56cf) Masonry fish pond. 44cf GBs. 200 gal (26.7cf) ST. 15 gal (2cf) RFF. 50 gal (6.7cf) biofilter. Brook trout and Comets.

Don't you start yabbies or we will have Stuart starting one of his rants Anyway what would you call layflats which have no rectangular pvc pipe with ridges?

Ok so the one on the left is nutrient film technique and the one on the left is nutrient flow technique then....
Is it not possible to run a nft system with round pipe then? Even if the pipe is angled with a constant flow passing through and a water height just touching the bottom of the net pot?

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Skeg In The Hills.

and.... does the NF(ilm)T water have to be constant flow or can it be timed in cycles?
What would be the advantages of NF(ilm)T over NF(low)T F&D MrDamage?

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Pete.

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No and probably no (high air to water ratio and the roots would dry out)

What are "layflats which have no rectangular pvc pipe with ridges"Sleepe?

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Pete.

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he meant with an open end, so it doesnt "flood at all", but has a small stream similar to real NFT.


NFT could also stand for "not film" tubes on those other forums / youtube videos.

Most of my research notes got lost in the computer crash a number of years ago however I still have the book by Sholto Douglas from way back. I found an online pdf http://www.fastonline.org/CD3WD_40/JF/413/05-189.pdf .
(Page 113)Remember this was many years ago when they didn't have black/white plastic and were pumping the solution through holes in an inserted hose.

The pots are filled with growing media with good wicking properties, so the nutrient solution wicks up through the media via capillary action. Usually perlite or vermiculte, or a blend. Coco coir is also used, but is not as popular. Expanded clay is sometimes used in larger diameter net pots, but not lettuce pots etc, and is far less effective in regards to wicking.

Some roots will grow in the pots/media, but the majority grow out of the pots and along the base of the channel, in the nutrient film, which is why it’s not a good idea for the flow to be stopped in NFT, as Sleepe suggested.

I would avoid calling the second design Nutrient Flow Technique, that’s only going to lead to more confusion. I would refer to it as Constant Flow or Constant Flood.

With NFT the water can heat up very quickly on warm days. Depending on the depth and volume of the water in the second design, it is far less likely to transfer as much heat to the water in your system.

With NFT, if the water stops flowing you have only a matter of hours, especially on warm days, before the plants start suffering or even dying. With the second design the plants would probably be good for days.

How would you do that?

Anything more than a film of water in the base of the pipe would not be considered NFT, and you’d need more than a film of water in order for it to contact the base of the pots in a round pipe, especially if the pipe is angled.

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Mr Damage - a.k.a: Yabbies
Owner at Perth Aquaponics - Aquaponic Consultant & Trainer
Trade certified Horticulturist & Cert IV TAE

lol constant flow or constant flood? we already have those for other things....

how about shallow water culture..... like we have called it here in the past....? :smug:

Thanks for the clarification and design pointers Mr Damage.

I'm intending to add two rows of 90 mm PVC around my System 3 bath tub setup to increase the GB capacity by using the over flowing pump time of around ten minutes through the Hydroton and plumb water through the side of the tubs and into the PVC.

Now, I'll fill it high enough so net pots can wick then let the end overflow back into the FT while maintaining the PVC water level during the 15/45 cycles. If the power fails it should easily survive the out time.

So I presume the system would be called A "timed media flood & drain with constant flood tube"???

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Pete.

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Ah, yes... the old TMF&DCFT system... but who knows, that's probably wrong.

What I can tell you for free is that I would not recommend using 90mm SWV pipe.

I would use 100mm DWV, it’s almost exactly twice the price (at the big red & green sheds here in Perth at least), but...

- It has 3x the wall thickness, so is much stronger and doesn’t need anywhere near the same support.
- Sunlight can penetrate the 90mm pipe, roots don’t like sunlight, but algae loves it.
- The thicker wall on the 100mm is more likely to insulate the water contained within it from external heat/cold.
- Depending on the size of pots being used, for the same sized pot, the hole will extend much further down the side of the pipe with 90mm, reducing it’s structural integrity and allowing sunlight in through the gap.

Also... Are you planning this addition to your system so there are more plants removing Nitrate and other nutrients, or so it increases your bio-filtration and therefore your safe fish stocking capacity?... If it’s the latter, it won’t provide that much more bio-filtration and there are far more efficient ways of doing it.

_________________
Mr Damage - a.k.a: Yabbies
Owner at Perth Aquaponics - Aquaponic Consultant & Trainer
Trade certified Horticulturist & Cert IV TAE