Backyard Aquaponics
A place to discuss aquaponics

Thanks Colum! I'm a big fan of all of your (YouTube) films , I'm glad to hear that my original design will work, and even better if I can use just one pump, do you think that a 6000 LPH pump would move enough water for 4 F&D cycles per hour? And is that a good amount of cycles for e bed this size? And what diameter do you think I would need for the standpipe and bell siphon?

Thanks for watching

It doesn't matter if there is one flood and drain per hour, or twenty, it'll both work the same. Size the pump to go with your fish tank size, so if you build a 4000L tank, get a 4000LPH pump. No point in wasting electricity if you don't need to, or extra money on bigger pumps.

The siphons will at different flows according to the size of the standpipe/bells. I found that 4x40mm standpipes were about the right amount for my 8000LPH pump, so if you went for 20mm (or 25mm since the pipe is easier) standpipes, and 50mm bells, it should work out well for the 4 beds. But that is a bit of a guess, the length of pipe/how high it pumps will have an effect on how well it works.

Do you think my design would be possible as one large u-shaped grow bed , or do I really need to split it up?

I'd leave it as one. You'd need the same size sump either way. Keep it simple.

Awesome! Thanks for your prompt advice!

I don't know if Colum is aware you're using a pond liner. With some of these, like durascrimm because it thin, it probably won't matter. With EPDM you're going to have a lot of wrinkles on the inside corners with bending the liner around the U. I wonder if just lining a box and putting a barrier inside of this for your fish tank would work better. Concrete blocks would raise the pH but something along those lines but without mortar would be permiable and allow flow out to the media on the other side. As long as fish were large enough they would be held within. One down side is the blocks take up a significant amount of space themselves.

thanks Scotty, i thought i would get a liner (epdm) a bit bigger than my whole system, cut a u-shape in it, and use the cut out shape in the middle for the fish tank and the u for the bed, additionally, it seems like this system may be extra difficult, so in parralel i have another idea i'm going to sketchup today, as for the concrete blocks, i think that any system i design will be using earthbags for the structure (great thermal properties, price, and strength) that are about 40 cm thick anyway

i just understood what you were saying scotty, i am now pondering that idea

I've thought about this for some time but haven't seen anyone do it yet. I wouldn't use the concrete though because of it's affect on pH but something else along those lines. I considered polymax chicken flooring or light diffuser grating aka egg crate. Don't know if either would work to hold the rocks back well enough and they might require a deeper bed if you don't want to do much cutting. Heavy blocks that stack have the advantage in some respects and are easier to stack at whatever depth but you might have more issues with trapped solids.

Lots of different ways to play with this. I think you could even have a 2 foot deep bed where it's a fish tank at one end and a DWC at the other but by having polymax suspended or supported off the bottom a foot, the fish could swim under the DWC portion without having access to anything other than the longer root sections. Smaller newly hatched fish might be able to hide in the roots above.

its a really cool idea, and probably very doable, but wouldnt DWC seriously limit the types of plants that i could grow?

i imagined a sort of marsh with one huge tank, fish in the middle, partition between the FT and GB, with an external filter for the solids pumping from the FT->swirl+solid filter->GB partition

That sounds a lot like a wicking bed type setup. You would need the external filters but it would be pretty neat.

You can grow most things in DWC but you have to provide support. It is easier to grow many plants in media. Ryan grows lots of things in DWC - this thread should keep you busy for awhile - http://byap.backyardmagazines.com/forum/viewtopic.php?f=18&t=12589&hilit=how%2Fforum&sid=90202bb9c0680ea2d5e6e4a145268221

You might want to do some research on ferrocrete, it might be easier (well in the end anyway), to get the shapes you want.

I've got a video if you want to see.

Thanks Scotty, and Colum, I saw the ferrocrete vid yesterday and am definitely considering it, it would be extra helpful for rounding the corners of the fishtank for circulation, and the corners of the grow bed to prevent dead spots, does the pond sealer keep out (and not contain itself) toxins ? And does it need to be replaced once in a while?

The concrete doesn't have any toxins that kill the fish (once it's cured anyway). The problem is the limestone content, it'll send your pH sky high. So you paint it with a pond paint that'll keep it out of contact with the cement.

If it's applied properly, it shouldn't need to be replaced. Well I hope it won't anyway.