Enough Gas Exchange?

[Myka]

Are you running a skimmer? If you have a skimmer, you can usually cover the tank without any issues provided the skimmer is getting a good amount of fresh air. Simply running the air injection line to the outside of the stand will greatly improve fresh air exchange.

[Ryan]

I have a cover for my aquarium but I leave a little gap for gas exchange, feeding hole and to stick my fingers in there to lift the glass if I want to get into the tank.

I have a skimmer on my tank and havent noticed any problems.