After having a reactor that kept dying when stirrers went out, I finally cut an eggcrate grid to fit a bucket about halfway down, dumped powdered kalk and ro/di in, let settle, and set, on that grid, a maxijet 1200 topoff pump with a modded locline delivery hose to go out from under a tight lid. The hose drips kalk under pump pressure from the topoff system.
First you set your alk/cal levels via dosing, then turn on said topoff/kalk reactor, and it will keep it there as long as your mg. holds up.
This is a discussion thread on same:
http://archive.reefcentral.com/forum...readid=1280638
I hope it helps. I've only had this arrangement running a week, but my levels are finally up and stable [no more stirrers playing out and timers going off] and the corals are *much* happier.