hydrophilia wrote:
Hey there, mate!
I just got around to seeing your thread. I know a lot of these are answers to old questions, but....
It is much harder to keep water 10deg warmer than cooler. Heat loss is through evaporation and, on a still day, a water surface loses heat as though it is about R0.1. Heat gain is much slower, with an R-value about R1 or R2, and via solar radiation that you can deal with through shading with cloth or a good cover of plants. Still, it would be nice to find a way to cool or insulate the exterior of that steel tank....
Because of this, I'd forget tilapia and go for trout (will eat voraciously even when water temps would kill tilapia and stop most other fish feeding, fast growing and entertaining, but need more pumping than others), catfish (perfectly happy with warm water and will survive cold, slow growing, but big), or bluegill (slow growing & tasty, same water temps as catfish).
I wouldn't soften the water. The iron and the calcium (if you have any) will be good for the plants.
Is that a stainless tank?! I'd probably use that for the fish tank with a tube running out the outlet, up to inner water height, then an air break T, and out to growbeds.
I'd slice the IBCs in half for growbeds. Put another IBC in ground as sump with some ply around it to prevent it collapsing. Rest one edge of two growbeds on the sump to keep it from floating out of the ground if the groundwater rises.
If you do use the steel tank for a growbed you could use a loop siphon (with large tube diameter), autosiphon, or bell siphon (same things topologically) and I bet you could get a 20 to 40gpm flow rate or better. You might not be able to drain it all the way as you need a good drop (a foot or so difference in water levels) to make that siphon work fast. Would you be happy only draining it a foot, then letting it fill again? It is a waste of gravel, but would certainly work while a deeper draining would be more iffy. You can try it and adjust...
Yep this is the route I am thinking about at the moment. Using the stainless steel tank as the fish tank, and cutting one or two IBC in half. I also agree it will be easier keeping the water colder then it will to keep it warm. Particularly since we only have about 2 months of really warm weather with 2-3 weeks being unbearably hot with high humidity. It would be hot enough to kill the trout though. (90-100F - occasionally 75F at night )
So trout it is.
I would go with bluegill except they take a bit longer to get to plate size. A full year or two vs the 6 to 9 months with trout. If i could keep the water from freezing then i would go with that system. Maybe the next system(s) when i get a green house and used the aquaponics set up as a heat sink.
So with the steel tank having a small exit. Would it work to go to a large diameter pipe immediately after the water leaves the tank. So it would be a bottle neck of sorts. I like the sound of placing a vertical 3 inch (or bigger) pvc pipe with a T airbrake, this would provide a constant height to the fish tank. It would be be a low flow high volume plumbing.
Then take the water to the grow beds. I would probably have to put some kind of flow regulation device so i can control the flow to the grow beds and keep them from filling and flooding in unison, and to fill at a decent rate for the plants.
The growbeds would then have a bell siphon and then drop to the sump with a float switch to take it to the fish tank. The fish tank would also have an aerator to keep the water moving in a direction that would help direct the solids to the exit.
Thank you for your assistance, it is really helping me figure out the set up.
Backyard Aquaponics
