Will CO2 bubbles ever fully dissolve in water? Background:
Many aquarists keeping freshwater planted tanks add $\ce{CO2}$ from a pressurized canister to their aquaria to promote plant growth. Injection is at a slow rate to get dissolved $\ce{CO2}$ in the neighborhood of 30 ppm. Methods vary, but a ceramic discs to release a very fine mist of bubbles are popular, as are $\ce{CO2}$ reactors which trap the bubbles in a bell or canister and stir them around with a water pump.
In any case, within the hobby there is an odd fixation on getting the gas bubbles to dissolve completely, I suppose on the reasoning that a bubble that pops at the surface is $\ce{CO2}$ that escaped to air rather than being dissolved in the water.
I'm skeptical of this logic -- I'd think while the bubble is dissolving, water vapor and whatever other dissolved gasses will be diffusing into the bubble. At some point the bubble becomes just humid air in equilibrium with the surrounding water, and no amount of stirring will get more $\ce{CO2}$ out of it. This is just my guess, based on casual observations where the bubbles will diminish to less than 10% of their initial volume within 30 seconds, and thereafter they don't seem to get any smaller.
Questions:
Is that correct, and does it mean the aquarist's quest for a &quot;100% efficient&quot; $\ce{CO2}$ bubbler that never lets bubbles pop at the surface is doomed to eventual failure?
And if so, what are the basic principles that describe this equilibrium and how can we figure how much $\ce{CO2}$ can be extracted from a bubble, and how big the bubble will be after it's become just humid air?
If not, why does it seem the bubbles will rapidly dissolve in the water at first, but never fully dissolve even though the solution is far from saturated?
To improve your CO2 intake and not lower dissolved oxygen levels, an apparent solution is to make the water in your fish tank more alkaline and also consider increasing the surface turbulence.
The logic is that there is an equilibrium based dissociation of CO2 in water creating Carbonic acid. However, in the presence of OH- ions, the formation of an insoluble carbonate (like CaCO3) will continue to drive the reaction to the right.
On the effect of turbulence from an air pump agitation of the water or perhaps a waterfall creating mist, will capture the carbon dioxide.
So, as solutions consider adding alkaline stones. There is also a supporting article: Limestone Rocks in Aquariums and Water pH, to quote:

Have you set up an aquarium and then noticed that the pH of the water continues to rise? Could rocks or gravel that were added as decor in the aquarium affect the water pH? Yes. If your rocks are actually limestone, they are the cause for the pH elevation in your aquarium water. Limestone is calcareous (contains calcium) and is known for its ability to both harden the water and increase the pH. In fact, if someone asks how to raise water pH, one method we suggest is to place crushed limestone, coral, oyster shell or any highly calcareous material in the filter.

On the waterfall idea a reference, to quote:

Speaking of pond health and waterfalls, they're a great way to aerate your pond, but you might not want to overestimate how much oxygen is getting into your pond from the waterfall. Specifically, the larger your pond is, the higher the waterfall would need to be to effectively aerate it alone.

Hope this helps.