Backyard Aquaponics
A place to discuss aquaponics

I was originally looking into hydroponics, but then stumbled across aquaponics, and as an avid fish-keeper I thought it seemed like the perfect way to grow some nice lettuce etc.

I've just started bathroom renovations and have an old bathtub that I'm thinking of using for a growbed. My thoughts are to have it up on my back deck on a stand, with a drainage pipe going through it to the plughole, and then PVC attached to the bottom of the plughole, and going down to a tub of fish/crayfish under the deck.

I'd have a pump in the fishtank that would pump up to the growbed and spray over the top of it with those spray nozels that come with the old blackhose irrigation kits.

Does this sound like a viable system ?

I should note, one of the reasons for putting the fish under the deck is that I could at some stage hang some clear plastic around it fairly easily to create a warmer environment for some warmer fish like Barra ( to survive the winter ).

I'm in the western suburbs of Brissie by the way.

Hi UT, welcome to the addiction

the spray nozzles would probably clog up with fish/cray poo, but apart from that it sounds good

Ahhh of course, I knew there was something not quite right about the idea. What do people normally do, use pvc with holes drilled through it ?

yep, at least 6mm holes, sometimes bigger

You dont want the surface to get wet (creates algae!) AP may take over your life! BEWARE!!!!!!!!!!!!
















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Which surface are you talking about? not quite following what you're saying.

Growbed surface ,others can give you more info but i think the GB surface should stay dry. Someone please correct me if im wrong!

Niloc means that we don't usually use drippers in an AP system as keeping the growbed surface wet (ie by dripping) causes the growth of algae on the surface of the gravel or whatever media is used.

The use of pvc pipes with 6mm holes as Jaymie suggested is fine in the traditional design... which fills the growbed with water up to a point just below the actually surface of the media... often about 15-25mm... then the drain cycle is started....

That way the media is wetted sufficiently without the top surface attracting an algae/moss bloom...

So if I want to design a continous system, I'd want to bury the PVC pipes feeding it with water under the surface of the media?

Most people use a growbed in a "flood and drain" scenario.... flooded then drained by a siphon of one sort or other. Usually the flood cycle is controlled by a timer or a float switch, which interrupts (turns off/on) the pump.

You can run a "continuous flow" in the sense of continually pumping.... but then you need to consider that the media will be continuously wet.... this can lead to significant problems with root rot and pyrethrium....

You would have to adjust your flow rates accordingly to allow the media time to "dry out" a little between flood cycles.... more importantly... the drain cycle needs to drain quickly enoigh to pull oxygen down through the media for root uptake.

Most people just lay the distribution grid for the water "flooding" directly on the top of the growbed media.

If you're thinking of a continuous flow hydroponic type system.. ala DWC... then that's a little different.....

There are some people that have run continuous flow in the manner that you described ... ala buried pipes, and "flood" the growbeds from below.... some with some degree of success, others with significant problems. I'll search and post later.

UT, just reading your desription again...

Was your intention to fill the bathtub with media, say gravel for example, with a pipe running through the gravel that was drilled with holes which would drip fed the gravel media constantly and the excess piped back out through the waste plug....

Is that what you meant by a continuous system?

If so then I think the above comments apply.

If the pipe was near the surface then all the media would be wetted somewhat and you could possibly balance the plant water uptake with the drip flow... but I think you'd have problems with any excess water in the bottom layers of the bathtub becoming stagnant and anerobic.

You need to incorporate a "quick" drain system/solution... like a siphon.

Best idea would be to use the tub waste plug with an upright standpipe siphon and a pvc pipe grid on the surface to flood the tub.....

I've been reading this site all afternoon and realise now that there's a lot more to know about these things than I first thought. So I'm going to step back a step and build a test system first.

I've got an old 3ft fish tank that I'll use for the fish and a styrofoam box for the growbed. The styro box will be higher than the fish tank, so will drain with an auto-syphon.

Here's a basic setup that I think will do what I need.

Once I've got it running I'll find a timer for the pump and that should give me a basic flood/drain setup.

Thoughts?

I just realised I drew the pump's pipe going right down into the media, in reality I'd sit it on, or just above the level of the media.

I've got a spinner that I had on an open sump filter ages ago that I might use for this, basically it's got 4 PVC arms with holes drilled all going in one direction. when the water pumps through it the force of the water going through the holes causes it to spin.

Careful with using a spinner, the water could be thrown out over the sides of the GB....this going continuously could mean a substantial amount of water loss