Is this cyano?

[LMDAVE]

I’ve had these spots in the tank a month or so, not much spreading. Tank is 4 months old. I can blow it off or scrape it off with brush. My sunny D zoas which are always open are all closed today and noticed a few spots on their rock also. Just curious if this is Cyano?

Nitrate 5
PH 8.2
Alk 9 dkh
Cal 425
Mg 1400
Phos 0.08
Salinity 1.025
Temp 79

 

[LMDAVE]

Any ideas? I need to clarify my original post since I can't edit it now, I meant to say I "can't" scrape this off or blow it off. Any chance this is coraline?

 

[Jason mack]

Yes . Then its probably coralline algea