Corals Dying

[Moogled]

My tank's been running for about a year now, and lately some of the corals are dying.

My Merulina plate coral started turning white on the edges and it has been slowly creeping across the coral; now it's almost half dead. I tried scrubbing the algae growth on the skeleton but it doesn't seem to be coming off. I dose Calcium regularly but I think there may be another problem. Corals don't seem to thrive in my tank with the exception of a Donut coral and a Scolymia

I'll post my water parameters tonight.

Any wide guesses as to what's happening or does the "whatareyourwaterparameters?" always apply?

Thanks in advance,

Marco