Black algae

Any ideas? Had bright green algae so we put in a phos-sorb pouch, now it looks as though the green turned black?????

 

sounds like cyano.. does it lift up in a sheet if you mess with it?

 

No, It looks like dust but I tried to use like a toothbrush to get it off and it don't come off

 

hmm ok i'm stumped. someone else i'm sure will chime in here

 

I have some hard black "algae" on one of my LRs as well. Doesn't peel off or anything, it's hard and relatively smooth like the rest of the coralline.

 

i think yours is a sponge.

 

blue green cyano. often comes in a hard black film almost that appears usually in like a circular pattern when it forms on the glass. Got a picture to confirm?

 

I'll try to post a pic.... See what I can do once I get home.