Bleached Coraline Algae -A Sign Of......?

[Zoaelite]

When you do your water changes do you drop the water level in the main tank right down? I used to do this until my return pump crapped out mid change and my tank sat half full for about 30 mins. Every bit of coraline above the water level died, everything below survived.

[DiverDude]

No, water covers everything at all times.