Steve, I don't know how to convert that calcium level but I keep mine at 460ppm. That is probably considered a high normal. I keep my alk. levels at 12 or less although right now I went to full strength kalk. and I'm up in the 13's for alk. right now. No problem just kicked 1 frag I had into wicked colors. :-D Do keep track for your magnesium too as that will allow the calcium to work at it's most optimun. I keep my mag. ~ 1200ppm. SG I keep at 1.024.

Salifert has test kits for calcium, KH and magnesium if you'd want to try them.