The pump that comes with it is fine. But that is a circulation pump. With a calcium reactor you have a pump to circulate water through the reactor, and one to feed water through it. They advertise it as a self siphoning reactor but do some user review research and that method literally never works long term.
A cheap solution would be to use a small utility pump like a maxijet or a small mag drive and have a fairly fast effluent rate (steady stream) which will prevent clogging of the line. My complaint about that method is you burn through co2 very fast.
Another option is to use a commercial grade continuous duty rated peristaltic like a masterflex or a Watson & marlow. They're not cheap but highly reliable. You can also fine tune the dose rate from a fast stream down to something ultra slow drip.
As far as regulators go I like the custom built dual stage regulators. There are a couple threads detailing part sourcing for masterflex pumps and dual stage regulators on the other big forum. I can PM them to you if needed
