It just isn't needed. If you feel the need to get your excess CO2 out, just run an airstone or powerhead w/ a venturi. Straight atmospheric O2 can be bad if taken in by labrynth fish, Cories etc.
Oh ok that makes sense, what about an Ozone like they sometimes use on a SW tank? I think it is O3 if i remember correctly. Been awhile since i looked it up.O2 isnt as nearly soluable in H2O as CO2. CO2 is 40 times the dissolve rate of O2. You would loose most of the O2 out the surface.
Conversely, CO2 is more easily/readily released from H2O.
Its very very common in reef tanks, helps maintain crystal clear water, it is done at very low levels.O_O interesting....never heard of putting 'ozone' into your tank.