Aquaponics - Thinking low energy

Just for a laugh, I thought I'd run the low energy aquaponics question through the invention engine yet again.

Yet again, it spat out something surprising.

So far we've seen it cough up a zero head system, and then try to raise and lower a grow bed by pumping air under it, then releasing it. We've seen some kind of wacky stepped air lift, and a device that dumps air from a small pump all at once to make it pretend to be a big pump, but only for a brief moment. That way, we might send a big lump of air acting as a piston to carry water up a pipe. (I think I might have missed one) That last one I think has some potential, and might also apply to this next one. But this most recent one is most interesting, and it's this...

If you put air into a media filled grow bed that's also full of water, the air should displace water. If the grow bed is attached to a fish tank so that the water can breath in and out depending on the amount of air flow, we should see something a bit like a zero head flood and drain system, running on a few second burst from a decent sized air pump, once every 20 minutes or so.

You would need to turn the air on and off so the grow bed breathed in and out and changed the tide.

Easily enough done.

With a big air pump only running for a few seconds every 20 minutes or so, we might see a turnover of fish tank water comparable with a standard system.

So we put a stack of air stones into a grow bed under the gravel.

We flood the grow bed constantly, and connect it to a fish tank so water can move freely between the two.

Each time the air is turned on for a few seconds, water is displace by the air, and the water level of the grow bed rises.

The water then overflows into the fish tank.

The air stops, and the water fish tank water flows back until the two are back to the same level.

Repeat as required to turn over the fish tank water every hour.

Maybe.