For context, my tank has been set up for about 4 months and was doing great with solid growth in soft, LPS, and SPS corals. Over the past couple of weeks, I've had a couple corals with receding tissue and some complete death. I lost a very hardy birdsnest and several others are looking rough. On inspection there seem to be some white sponges growing on the base/sides (first picture.) Here are the latest parameters and some photos. Any suggestions would be much appreciated. Thanks!
Salinity: 35ppt
Temp: 78
PH: 8.1 average
ALK: 8
Nitrate: 3
Phosphate: .03
Salinity: 35ppt
Temp: 78
PH: 8.1 average
ALK: 8
Nitrate: 3
Phosphate: .03