runaway calcium levels

[wingedfish]

My tank is 6 months old and since january my calcium levels have risen from 460 to 600. Five days ago I tested and found 580 cal and 8 Dkh 7.8 Ph. Added Kent buffer (washing soda) for ph and alk thinking the corals would use up calcium and got it to 8.2 and 12 Dkh a day later. Today tested and fount 8 Ph 10 Dkh and 600 Cal. Some sps is bleaching but everything else looks fine. I don't dose anything besides spirolina food pellets. Mag levels were also high at 1600 but have since dropped to 1450.

How detrimental is this problem? Where is it coming from?

Is there a way to drop calcium levels besides massive water changes? Is there a way to force calcium carbonate precipitation with high alk (proportionately high ph) and not hurt anything?

I'm thinking 20% daily water change for a week should get to purer water. I'm using Kent salt which mixed to 1.026 yeilds 9 Dkh and 480 calcium.

[Borderjumper]

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!