On the problems with the reef tank. First thing you need to do is a water test. You need to look at Ammonia, nitrite and nitrate, ph, calcium, alkalinity, phosphate. A healthy reef tank should have.
Salinity= 1.024 - 1.026 sg.
Ammonia=0
Nitrite =0
Nitrate=0 to 10
PH=8 to 8.3
Calcium=350 to...