Please let's keep going on this as many folks may be interested in our conclusions (especially Ron).
I am not only not familiar with CO2 injectors but have never even seen one so please "bear that in mind" with respect to my verbiage set forth below.
Air bubbles would not exist without surface tension.
Do you agree or disagree?
I have never therefore believed that the transfer of atmospheric gasses through the surface of the bubble was very, very minimal.
If the air bubbles could "somehow be broken up" in such a manner as to not form smaller bubbles then increase oxygen saturation might be possible. If you agree that oxygen gets dissolved there then you must agree oxygen gets dissolved from a bubble at greater depths.
I do not.
Smaller bubbles have greater surface tension per unit of surface area with respect to volume than larger bubbles.
A bubble will expand as it moves toward the surface due to the pressure (potential energy) at the lower depth. the surface of your tank is just a big surface of a bubble (that bubble being the outside world).
I do not think so.
An air bubble exists in the water medium due to surface tension.
Yes surface tension exists on the surface of the water in the tank but is about epsilon^2.
Hence the significant exchange of atmospheric gases to the tank water at the surface and not via the air bubbles. (unless they are partyin while i'm in bed, lol).
This is a good one!
I am not being an adversary here!!!
I would enjoy working through this one as I have never "run into" this issue being discussed in the literature and you are probably "way ahead of me in" chemistry and fish care.