I currently started having LIVE PLANTS on my 30G with four Orandas goldfish. Now, having a LIVE plant does add great feature to my tank. But my concern is since I have LIVE plants, it requires it to have CO2 for the plants thrive. Does anyone know a good size CO2 for 30G, any brands? I have seen DYI CO2 diffusers etc but before I go that route wanted to know if anyone knows a good brand to try. Is it harmful for my goldfish to have CO2? Any advice and guidance would be much appreciated. Thanks good_very.gif