I was listening to one of Bob Lusk's Facebook Live videos today where he was talking about aeration (I think it was an older video). He mentioned something that was probably minor and well-known to most people, but I wasn't aware of the fact that the tiny bubbles created by your aeration system aren't what adds oxygen to your water, its the pushing of the water in an upward motion, where destratification occurs, and where water can mix with oxygen at the surface. Wow. [Insert Mind Blown Image Here]

So I got to thinking... if the majority of oxygenation takes place on the surface, and if you want to mix as much water with the surface as possible, isn't your typical bottom diffuser a super-inefficient way of doing that? I'd think that paddle wheels or even fountains would mix way more water than the bubbles given off from a diffuser.

And I got to thinking again... wouldn't normal fish movements also stir up the water? Probably minor, of course, but depending on the size of your fish, I could see a lot of surface agitation/aeration coming from normal feeding habits and/or swimming.

Now I'm picturing a 50-ft tall inflatable Bob Lusk, sitting in a pond with a giant spoon, stirring it up.

It's not so much the agitation of the bubbles, but more the fact that you are exposing non-oxygenated water to the air/water interface (surface of the water) where it freely picks up the oxygen. The diffuser is merely a pump that moves lower water up to the surface where it can be exposed to the air. According to the Vertex lift chart...a single 9" diffuser (at 10 foot deep) can move 1600 gallons per MINUTE. That's pretty efficient considering it is being done with fraction of a horsepower.

Yeah, that's what I was saying. Its not the bubbles that are adding oxygen to the water, like I originally thought, its the upward motion the bubble stream creates to get water to the surface where it can pick up oxygen. 1600 GPM seems like a lot, though. I wonder how they're able to calculate that, because any motion whatsoever in water creates a ripple effect. If I throw a rock into a pond, that will cause the entire pond to "move". Maybe I'm just overthinking it lol.

A key part of this equation is moving bottom water to the top. Ponds stratify. Bottom water has no chance to absorb oxygen or relieve itself of gases as they build in that cold layer. Diffused aeration provides vertical movement of water, where a rock thrown into a pond only offers horizontal movement of what that interfaces with the atmosphere anyway. That's the biggest difference.

I'd love to see that big spoon.

Yeah, and it's strange that the best way we've come up with is using a stream of tiny bubbles to move the water. You'd think you might be able to get better water movement with just a direct pump, pumping water vertically from bottom to top, no bubbles.


I'm working on it.

Steve:

Energy wise it is cheaper to move the water to the surface with the bubbles than to pump it. A LOT cheaper.

Yeah, I was kinda thinking that. Water has a lot of resistance, and anyone that's ever used a row boat can attest to that. I can imagine the energy consumption if you tried to rig up some sort of underwater paddlewheel. I guess tiny bubbles it is.

Don Ho agrees too!