[Son Of Skyline]

I've been looking at calcium reactor diagrams, and they all have a CO2 inlet. Where does this CO2 come from? Do you need to buy a separate CO2 canister that you have to keep filling/replacing when you buy a reactor? Also, do you have to have a sump to run a calcium reactor? Or can I just have it going through the main tank? TIA [img]smile.gif[/img]