720ppm of Ca?!!!!

[pocilipora]

I wouldent trust Hagens test, I wouldent even bother testing calcium levels. Only test and adjust your alkalinity. That salifert test kit works well for me. I usualy keep between 11 and 12dkh, but I have gone as high or low as 15dkh. If your calcium got that high, it would have precipitated out of solution and you would have what looks like a snow storm in your tank. Id blame the hagen test kit for a false reading. Do you have a reactor?