Jeff, I also use both. I dose B-ionic every few days and kalk in the topoff. I also run a single stage calcium reactor. I have always had trouble keeping both my alk and calcium up. I am getting better results when I dose the B-ionic every other day or so. When I just rely on the kalk in the top off and the calcium reactor my alk and calcium fall over time. I have quite a load of sps corals that seem to be sucking up the stuff .