one thing i was thinking about for you... if you are injecting co2 into your tank via your canister you may be wanting you push the saturated co2 water down into your tank(i know this goes against what i said before)... maybe just get a small powerhead to create the surface roll...
this way you know the co2 you are injecting is going to be getting moved around your tank throughly and not have even less potential of getting off gassed
this way you know the co2 you are injecting is going to be getting moved around your tank throughly and not have even less potential of getting off gassed