I was using kalk in the ato for awhile, but I kind of got tired of adjusting it. So switched to two part on a cheap doser. Calc and alk are both on the doser. I was slacking on the calcium and getting it setup on the doser for a while. Calc got down to 300 . My mag barely seems to move, I was using reef crystals till about 2 or 3 months ago, switched to fritz. I had to adjust the alk on RC with acid, got tired of that to so switched to something closer to what I wanted to run my alk at. I shoot for pretty much the same numbers as you.