Aquaponics - New air lift design

If you pump air down into a submerged tube, when the bubbles rise to the surface, by virtue of the fact that they take up some space, they change the average density of the water in the tube.

The result is that the new, lower density water floats, and you get water sticking up above the surrounding water.

In short, you get a pump.

This is nothing new, and even if all you do is stick some bubbles at the bottom of an aquarium and let them rise to the surface, you are seeing what has become to be known as an air lift.

Through the introduction of air into water, the bubbles cause a vertical current.

If you stick those bubbles in a tube, you create something of a pump.

An air lift in an aquarium is mainly used to create current and keep the top surface of the water moving. This top surface is exposed to the oxygen in the air, and the exposed water gains dissolved oxygen, or DO,  essential for the ongoing good times, and life, of the fish in your aquarium, or aquaponics system.

I don't have an air pump, because I run so much water through my pump, that it's not necessary. I do run a powerhead, which is a lot like a little outboard motor, that achieves the same thing, and in my case is totally unnecessary because, as mentioned, I pump so much water with my over sized pump.

An air lift, and a powerhead both move large amounts of water for a small amount of energy. My 5000L pump was 150 watts, my 5000L powerhead is only 13 watts.

The difference is the pump could lift water 5m, and the powerhead cant really lift water at all. All it can do is stir it.

An air lift can lift water, but it's a bit limited in how high it can lift it. It would be nice if an air lift could lift air to a greater height, because then we could create a really low energy aquaponics system in a conventional (grow bed above fish tank) arrangement, and still get the desired flow.

To this end, I drew this.

Normally a picture might paint a thousand words, but this is a picture of particular poor quality, so I'll need to add a few to make it paint up to around 150.

Picture a pipe with some chambers, all sealed and air tight, so whatever pressure is in there, stays in there.

If the air lift were to deliver it's water to a chamber, the water and air would separate.

If the air was then bled off from the chamber, and re-introduced under the collected, chambered water, it might be reused to create a second or third (etc) air lift.

This might mean we could lift air higher than with a normal air lift.

I have no idea if it would work, because I haven't been able to rope anyone I know who runs air in their system into trying it yet.

If I cant get anyone to test the idea, I'll have to buy an air pump.

Either way, I'll let you know if it turns out to be interesting.



120 things in 20 years, bringing you the vaguest suggestion of science in the hope that someone else will do the actual tests and see if my aquaponic, new air lift design actually works.