shouldn't affect the Ca
I was going to suggest a kalk
stirrer, which would help raise and maintain the high pH you are looking for, but it looks as though you might have Ca
issues as well.
Granted my experience is limited (I have kept aquariums for years but my first reef was started at the beginning of this year) but I found that fluctuating levels of Ca
played havoc on the coral - and after adding a 2 part dosing system, coral growth exploded. Stability and proper levels seems to be a key to success.