Backyard Aquaponics
A place to discuss aquaponics

I have a 5800 liter tank. Is was thinking of filling up the lower half with gravel. Leaving a well in the centre ie large pipe going from water level to bottom of tank. Holes at the bottom of the pipe. Pump sucking up from the bottom. Using 100 X 4m by 10cm polypipes filled with gravel, holes bored in the top for plants. Gets around trying to make grow out beds.

This will work no worries Matt. There are many people using poly pipe, or NFT guttering for growing the hydroponic side of their aquaponics, though there are a couple of things to keep in mind.

Firstly, you need to remove solids from the water before pumping it through the pipes with plants. This may possibly be in the form of a settling tank. And you may even need more than this for enough solids removal, the UVI system components page is interesting to give you an idea on what type of components are required for these other methods of hydroponics. Although their system is using rafts, NFT is very similar in the requirements of water clarity/solids levels.

This is part of the reason why I love the growbed system so much, the simplicity of just pumping the water straight into the gravel.... OK, ok, only simple if you can get decent materials for making growbeds...

Finally got my pc fixed.

Joel I was still planning to have gravel in the pipes would I still need to remove the solids?

I don't know Matt.... Sorry I can't give you a better answer than that but it's something I have never tried, so I'm not sure what type of results you would get.

Does anyone else have any further ideas? People with more aquarium experience, any ideas about the gravel in the tank with a pump at the bottom of a pipe?? Is that a bit like an under gravel filter?

I have used undergravel filters with success in smaller systems In one your size you'll want a good pump to pull through all that gravel and give the flow you require. Continuous flow all the way with pipes I never thought they were much good but it could have been my husbandry skills

Why I didn't like them

Too small for roots for most things
Pythium problems not seen in beds or DWC but present in nft
Ends of rows lack nutrients. Individual plant plumbing too fiddly.

NFT Systems won't pull nutrients out of the water as effectively as a gravel growbed.

According to Wilson Lennard, DWC is almost as good as gravel.

Can somebody tell me a bit more about DWC. Doesn't it stand for deep water culture. Can you explain the method a bit please Gary.

Thanks.

excuse me...
What is DWC

Anyone feel free to correct me i miss something. DWC stands for Deep Water Culture.

Plants are suspended in a liquid nutrient solution (fish water for us) with direct airation of the roots (doesn't need to be direct actually, as long as the water is 100% 02 saturated)

The roots don't rot as there is ridiculous amounts of oxygen in the water, and DWC is actually meant to have GREATER growth rates to all but the aeroponics method

Is there a simple way to O2 saturate the water and is it a good thing for the fish? Sorry if this is a silly question.

Sorry 'bout the jargon.

DWC stands for Deep Water Culture - it's another form of aeroponics.

In a DWC system the roots of plants are immersed in water with a bubbling aerator which keeps the roots oxygenated.

In an true Aeroponic system, the roots are suspended in a chamber. A pump ensures that the roots remain wet while providing a maximum amount of oxygen.

Either way, the oxygenation of the root zone of the plants is the secret behind the productive potential of DWC (or aeroponics).

It is relevant to aquaponics inasmuch as it is a means of removing nutrients from the fish water and providing them to the plants. The water from the fish tank is pumped through the nutrient chamber where the roots feed

The benefit of DWC over true aeroponics is that, if the aeroponic misters cease to operate, the plants suffer - very quickly. With DWC, there is direct contact between the roots and the nutrient solution.

There are several ways of ensuring oxygen levels are maintained in a DWC system.....including air pumps, compressors or bottled oxygen.

When using DWC for aquaponics, is the airation occurring in the chamber, or in the fish tank?

The simplest way is via the standard air stones and air pumps. And from what i have read although aeroponics has more growth potential its not by much.

Another thing that i was always wondering about is that floating raft is in essece DWC. As long as there is O2 saturation then there is no theoretical difference in having a bubbler directly under the roots.

Steve - not sure I am clear on that answer. I understand that an air stone can provide the o2, but is it in the fish tank or in the chamber? Does the water flow through the chamber like NFT at a very shallow rate, or is there always a decent pool of water in the chamber?