Do you think it might be possible to have a viable system that has the beds flooded every 8 hours, by hand? I'm imagining a bed lowered with a car jack to a level below that of the fish tank, thereby flooding the bed. Then, the bed is hand-raised by the jack back above the fish tank level. This is done every 8 hours, which would allow for 3 times a day (not too inconvenient). To keep the bed from drying out too much, those round balls in seed starter soil could be added, as they act as slow-release sponges. And, the fish tank could be conical in shape, so that the poop collects at the bottom so that when the bed is flooded it will be sure to get all of the poop at once. Could a balance of fish density and plant density be obtained to create a balanced system, and not require a pump? Thanks for your opinions on this.
The short answer is how much time do you have and how strong are you? I suppose it's possible for you to have say ten fish in a 350gallon tank with two cut barrel grow beds, but even that is heavy. If you truly hate the sound of pumps, or whatever, you could design a system that you run constant flow and a external power source has the sump tank on a conveyor when the tank volume gets below a certain point, but I suspect not only will the sump be too large to make any energy savings that you'd have difficulty with external power or a car jack. The drain of the sump will be significantly closer to say 2 1/2 hours than 8 hours. Again, how strong are you?
I wasn't thinking of a sump system, just a fish tank and a single grow bed. A system of pulleys or gears could make the raising/lowering of the bed not too strenuous. I'm trying to design a system for 3rd-world countries, where maybe they don't even have electricity.
... I have read that if you are talking about genuine 3rd world applications then getting a stable and regular supply of fish food could be a significant problem to have to consider.
Yes, I started another discussion under "fish topics" called "No external fish food?" to address that very concern.
Your best bet would be to leverage the work done by Travis Hughley at FASTOnline.org. Namely review "Aquaponics in Developing Countries" and "The Barrel-Ponics® Manual". I was going to use his Barrel-Ponics manual while in Afghanistan, when I was serving with the Marine Corps. Rather than using a pump, we would have filled the 'header' tank manually, until a pump could be procured. Obviously, fish densities would be low. Additionally, we would have opted for a locally available carp, that could withstand lower than ideal dissolved oxygen.
Thanks, I read those two things, and one still has to, as you point out, get the water up into the upper tank. I think a hand-operated lift table seems easier (no scooping of water). As far as aeration goes, I was thinking the pond would be rather shallow, to have more surface area. But, it's all just an idea, I don't know if it can actually be done successfully. Thanks again for your thoughts.
Looks like Japan Aquaponics has a great idea to share.
Some other designs:
Thank-you Japan and Ellen for those nice ideas. Of course, since the beds can be placed on a platform, instead of moving the water I could just move the bed, with an appropriately designed platform (then let gravity do the water movement).
The real question though is whether this can be a viable system? If someone did this every 8 hours, and made an effort to collect all the fish poop each time, and the fish pond was shallow to provide aeration, and the grow beds were kept moist (using the sponges I spoke of, or by way of slow draining), could an appropriate ratio of grow bed to pond ratio, and an appropriate fish density be found? Maybe there would still be too much ammonia build-up?
Before I attempt it, I just wanted to get some opinions. Thanks for your help!
It would be possible. The biggest issue that I see would be flooding the grow bed enough to keep the ammonia down so you don't kill the fish and bacteria. It might require more floods than once every 8 hours.
It would require lower stocking densities, but if you channel the water draining from the grow bed to break the surface of the water... yeah, I think it's plausible. Slow drainage would be a must for the bacteria to do their job. Keeping the media moist for 8 hours in the hot sun could be a trick.