Check your phosphates. You can kill corals a lot faster by having phosphates a little to low than having phosphates way to high. Here's an interesting qoute by Chalres Delbeek "When I see the colors of some of these low nutrient tanks, I can't help but be reminded of bleached corals reefs . . . Our crystal clear aquaria do not come close to the nutrient loads that swirl around natural reefs." For more reading:
Phosphate uptake in corals
http://jeb.biologists.org/content/214/16/2749.full
Ammonium uptake:
http://www.ingentaconnect.com/conten...00004/art00011
Nitrate uptake:
http://www.aslo.org/lo/toc/vol_48/issue_6/2266.html
Fish as major carbonate producers
http://www.pnas.org/content/108/10/3865
Effects of Anemone fish on anemones:
http://www.tandfonline.com/doi/abs/1...9#.UpS4pyeJ7Mo