You don't need a calcium reactor unless you're not able to keep up with calcium/alkalinity/magnesium demand with water changes/2-part dosing/kalk reactor. That typically means you're SPS/clam heavy. You don't need anything of the sort if you're just keeping fish in a fowlr.
You don't need it,even if you keep a lot of SPS you can keep up with 2 part.I actually prefer 2 part to a calcium reactor.I have it set up with 2 dosing pumps on timers.Works great.
