Tank Problems

Hi every one, Im Glen Winter and i have just registered on this Forum, I have a 75 gallon Reef Tank and Ive had it 5 months and what to keep SPS corals, My water levels are SG 1025, Nitrate 2, Phosphate below 0.03, Mag 1270, Cal 450, dKH 12.5, I have introduced Montipora,s and Acropora and they have all stripped with in a week, any body any ideas what could be the problem, my local shop where I got my tank set up from has told me that its not a lighting problem as they are stripping from the bottom