NFT. (Nutrient Film Technique)

[Murray]

I have just set up my first NFT "add-on" to my current system. I have the seeds into the seed raising trays and the water is flowing through the system. All is ready for the spring.
The timing should be good, the cold weather will be passed by the time the seedlings are big enough to go into the NFT system.

The first NFT system will run water directly from the fish tank down through some grow pots that are 300mm deep filled with gravel then drain through the NFT channel. The grow pots will act as mini bio-filters. The NFT system is getting its water from the same water supply grid as the ordinary grow beds, so the pots will be needed in the mini-nft system to do the same job as standard grow beds do.
At least, that is the theory. So I will be running daily tests on water in and water out to see if bio-filtration is taking place.
Any suggestions ?

[damien little]

if you are running it as an addon, you won't be able to tell if biofiltration is taking place as your system should already be cycled up

[Murray]

Yes Damien, it will be a bit difficult to tell, I have thought through that aspect of the process, but I believe I should see some difference in the "out" water to the "in" water. It will be an interesting set of observations.

The most important part of the cycle will be for the mini pots to remove and retain the "solids" that are in the water coming from the fish tank.

[Handyandy]

Hi Murray,

I have an hydroponics background (recently converted to aqyuaponics) and don't want to be critical, but this is stricly not an NFT set up. using pots filled with media in channels is a media system, not NFT. NFT uses no media and is designed to confer other advantages (ie: high oxygen at the root zone).So, as I said, don't mean to critizise, but i reckon the dsiticntion needs to be made as people may think your set up is NFT, when it isn't!

Still, I have tried this type of system and it works fine. As for biofiltration (from the other reply), you get plenty of bacterial growth area even if you use this system as the pots have a lot of media in them.

Handyandy

[Murray]

Thanks Handyandy,
Yes, I guess that strictly speaking you are correct. However, I am trying to mesh together the best of both worlds, which is what Aquaponics is really all about. The meshing of Hydroponics and Aquaculture. Obviously there are loads of ways of doing this and my new little experiment is a way of partly processing the water from the fish tank (mostly to remove the fish waste solids) from the water flow before it is sent down the NFT channels.
I believe there will be a bio-filter effect taking place in those pots.

Some large commercial Aquaponic systems go to a lot of trouble to remove those solids before sending the cleaned water off to the NFT channels. Skimmers, filters of various types etc.
Often they are left with a pile of very nutrient rich fish poo that they just run-to-waste, which is a bit of a shame.
Some others compost this waste together with the trimmings off the plants they grow in the NFT channels and sell that composted material as a by-product of their activities.
Still some others use this solid waste to grow a worm farm.

The beauty of a gravel grow bed flood and drain Aquaponic system is that the solid fish waste is perfectly used up in the gravel grow bed. The water that comes out of the bottom of the gravel grow bed has had the ammonia converted to plant usable nutrients by the friendly resident bacteria.
The resultant goo in the gravel grow bed is great for growing fruit bearing plants such as cucumber and tomato.

[sillyoldfart]

That Ell-Gro pot or bag system from Boxsell Hydroponics is just the bees-knees eh Murray.

Can't see any reason your idea wont work Murray. Indeed the whole Ell-Gro system shown is designed as it is to return the nutrients from the pots back through the channels to the reservior.

Albeit the pots are usually drip feed to clay filled pots with normal hydroponic nutrient solutions, but the idea of feeding them with the AP nutrient is just a straight substitution with the addditional benefit of the solids providing the essential trace elements that you would have to add with a traditional hydroponic system.

I've used a small hydroponic setup almost identical to what you have pictured for nearly a year now and aim to convert it to AP as soon as I have the funds to build my AP system.

I see this as a better option (no criticism intended) to Gary's idea of satellite pots as any excess water is returned and it can be incorporated into the "timer" cycle so that manual watering of the pots isn't required.

The added benefit of what you have pictured is that you can use the other channels to grow lettuce and herbs in net pots with the returning water.

A word of caution though. While I initailly setup my Ell-Gro channels virtually as you have pictured Murray, I found that drip feeding the pots provided barely enough flow and nft solution for the other net pots in the remaining channels. Ultimately I ended up supplying the other channels directly (additionally) with their own drip lines.

As you are supplying directly through (looks like) 25mm pipe this may not be as much of a problem, but watch your flow rate through the remaining channels, especially in warmer weather.

You may not have enough flow otherwise. Conversely if you up the flow to provide the lower channels you may be over "watering" your pots and bags.

I'd suggest using a very quick draining media in any pots or bags, certainlly not coco-peat.

[fishfood]

Hi this is my so called nft system using filtered fish water its been running 12 months now hove had lots of lettuce last summer now planted out with strawberrys

[GaryD]

Hi,

I see this as a better option (no criticism intended) to Gary's idea of satellite pots as any excess water is returned and it can be incorporated into the "timer" cycle so that manual watering of the pots isn't required.

The Satellite system has exactly the same capability as this system inasmuch as it can be recirculating. The reason that it doesn't recirculate is that it uses coco peat.....so it doesn't need to recirculate.

If my satellite pots contained media like gravel or expanded clay then I'd recirculate them.

Gary

[sillyoldfart]

Hi,



The Satellite system has exactly the same capability as this system inasmuch as it can be recirculating. The reason that it doesn't recirculate is that it uses coco peat.....so it doesn't need to recirculate.

If my satellite pots contained media like gravel or expanded clay then I'd recirculate them.

Gary

I'm sure that is the case Gary.

As I said "no criticism intended". The discussion concerns recirculating water return via an "nft" style.

The way your system is currently set up and the fact that you use coco-peat means that you couldn't run it as a re-circulating system through nft. Or at least I don't believe so, and that was exactly the point I was making.

I certainly like the idea of utilising the return flow through nft to maximise the utilisation of the nutrients for more plant growth. Also as I said it enables the "whole" system to be controlled by "timer" and any excess water captured

You have chosen to do it another way and using another medium. I don't imply any criticism or doubt the validity of what you're doing.

[GaryD]

Hi SOF,

I didn't take your comments as criticism.

My comments were a response your observation about your preference for the Ell-gro system because "any excess water is returned and it can be incorporated into the "timer" cycle so that manual watering of the pots isn't required".

I was making it clear for those readers who may not be aware of what satellite pots are (much less how they work) that any difference comes down to my choice of media......otherwise the manner of their operation is almost identical.

Gary