| | Re: CO2 in my planted tank
CO2 leaves the water as easily as it enters. When it enters water, some of it forms carbonic acid, lowering the pH. When it leaves the water, the pH rises again. If your fish aren't gasping and plants are healthy, you're adding adequate CO2.
As for the bba. It doesn't have to do with CO2 directly. CO2 doesn't kill it or anything. You'll just have to get used to it or burn the tank down. You can control it though. Lower your light intensity, weekly water changes to direct dosing of excel or peroxide. On hardscape that you can remove, take it out and spray the whole thing in peroxide, wait a few minutes, hose it down, and put it back in the tank. Clean out your filter once in a while too.
Your pH regulator will need monthly calibration btw. Sensors will drift and will give you inaccurate readings.