starting a coral tank

[eWarren]

I have a 75g fish tank for a year and a bit more. Recently I am trying to do coral. So, I divide one third of my 75g into a reef tank. I am not sure what's missing in my tank, but some clove polyps I bought from J&L which used to regularly open and close their "hands" when they were in shop does not do it anymore after came into my tank. And I also seems have trouble to bring my calcium level to 450. Currently, my ca reading is around 350 to 390. Mg is about 1100. Use Instant Ocean's salt mix. Kent turbo ca. Alkalinity is about 9.8 dKH. Any one can give me sme himt? Thank you.