WHAT TAKING OVER MY ACAN?

[GreyYeti]

AND WHAT CAN I DO TO REMOVE IT BACK TONORMAL?

 

[Jekyl]

Does it easily blow off? Looks like cyano

 

[Lyss]

mesenterial filaments. Prob reacting to the water change referenced in the other post about this.

 

[MaxTremors]

Definitely mesenterial filaments. Something had disturbed it. Usually see this when something has physically upset a coral (like moving it, a crab or shrimp bothering it, another coral stinging it, etc.), though water quality issues/instability can cause it also.