I wouldn't worry about the calcium.. It's a little high but leave it alone and the corals will use it up.
IMO your stressing your corals playing with the alk. Going from 8 to 12 in a day or two is pretty drastic. What's wrong with 8 DKH and 7.8 ph?
I messed up my CA for a while, lol I was doing the salifert test at 1/2 strength, but them forgetting to double my result.. So I keep adding calcium, adding calcium.. By the time I realized that I needed to double the result I was up to like 800.. Everything still was happy.. I just let it get used up and it naturally came down in a few days. I think we sometimes make things much worse trying to make them better!
