Coraline question

[Dez]

I have a question, has anyone ever had their coraline algae die off on them? I had such good growth on my glass and powerheads....then when I woke up this morning, most of the coraline on my powerhead is turning white. Everything tests out fine (calcium at 420, alk at 10, Ammonia/Nitrate/Nitrite - 0, ph 8.3...and don't have kits for anything else. I thought it might be phosphates? I did start feeding daily from once every few days because I recently added a school of Anthias and they need to be fed daily (at least). Anybody have any thoughts? I hope it doesn't continue dieing...

Thanks guys,

Des