Actually, that is a bit backward. CO2 dissolves into water much easier than O2 does, and it also comes out of solution equally easy. So, this method does speed up the absorption of atmospheric CO2 into the water, but it also speeds up the loss of CO2 to the air, due to the water surface disturbance from the bubbles. So, you will get no net gain in CO2, above what you get with a quiet water surface, but you are probably getting more of the CO2 down into the lower water to replace that used by the plants. Just good water circulation in the tank will do that too. If you don't like seeing those bubbles, just using the Koralia to keep the tank water moving will do the same job.
Hoppy, thanks for setting me straight. I guess I misinterpreted something I read in the past.
One thing though, if an aquarium were getting its CO2 from only atmospheric exposure (ie, surface exchange and bubbles from an air pump), would the gain and the loss not be pretty much equal?