Co2 diffusion in water questions

Hey so I have a question about co2 and diffusion in water. I have had co2 running on my planted tank for weeks now. I notice some things and have questions. First questions, most of the bubbles rise from the diffuser in fine bubble to the surface, even if blown about by the HOB. They eventually just rise up and pop at the surface. So my questions is, is any of that actually dissolving in the water? Is this even possible? Isn't it the same as air bubbles rising to the surface? They just rise up and dissolve into the air above the aquarium? If this is the case, how is this any good for the plants. Don't get me wrong, i've seen amazing growth from my plants in the past few weeks. I've been dosing ferts, root tabs, everything they need. So I do believe co2 is helping a ton, i'm just wondering if what's happening is a small amount of co2 is getting to the plants and then the rest is a waste and goes up into the air. Second question, will having the bubbles diffuse directly into an aquaclear powerhead help? I have heard that this can act similarly to an in-line diffuser on a canister. And gives a superior dissolve rate.

 

No, not much is dissolving in the water. The bubbles rise, pop, and through gas exchange and surface agitation its absorbed into the water. That's how it works. Its good for the plants because its EXTRA CO2 at the surface that's getting absorbed back into the tank. That's why you limit the amount getting released and the length/amount of time its being run. Otherwise it would kill the fish.

 

No, not much is dissolving in the water. The bubbles rise, pop, and through gas exchange and surface agitation its absorbed into the water. That's how it works. Its good for the plants because its EXTRA CO2 at the surface that's getting absorbed back into the tank. That's why you limit the amount getting released and the length/amount of time its being run. Otherwise it would kill the fish.

So will the powerhead help? I figured this was the case.

 

No idea. I don't see why a powerhead would help in dissolving them further, but maybe it would. Its really the surface agitation that puts it into the water as CO2 is heavier than 02 so it doesn't just float away when it pops. It sits on the surface and gets put into the water that way.

 

I try to aI'm mine to the outlet of the hob.
Gets co2 blasted back into the tank.

 

No idea. I don't see why a powerhead would help in dissolving them further, but maybe it would. Its really the surface agitation that puts it into the water as CO2 is heavier than 02 so it doesn't just float away when it pops. It sits on the surface and gets put into the water that way.

Ahhhh, gotcha. That makes sense, I was wondering about that kind of thing.

 

There are numerous studies spanning decades on the mass transfer of oxygen in bubble plumes. They've found that 95% or more of the total mass transfer is via bubbles with very little surface transfer. Other studies have found that surface aeration is much less efficient than bubble aeration.

CO2 has a few things going for it that oxygen doesn't--it's more soluble in water and it's ~99% pure. I would just put the diffuser as deep as possible and not worry about it.