Plants Producing Oxygen Bubbles

[RianS]

For a canister or canisters if you're willing to spend money. I would either suggest an XP3 or a 2217 with a powerhead/wavemaker for added turnover/distribution of co2.
Some people may suggest 2 2215's or 2217's for a better biological since you can periodically clean one every so often and keep a sufficient amount of biological with the other canister.

 

[plamski]

I have Eheim 2217with one of those:
http://cgi.ebay.com/CO2-Carbon-Dioxide-Diffuser-Dispenser-Aquarium-fish_W0QQitemZ110490468943QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item19b9bec24f
in one side.
The same like yours in other side of the tank. Much better to diffuse in 2 places. If you go with more than 2-3 bps CO2 thru canister it will create air bubble in it. At least mine doing it. Otherwise 2217 is great