Cyano???

[G1GY]

Originally Posted by Murminator

The coraline aglae on my rocks have been turning into a deep deep burgundy colour almost black. It seems smooth to the touch not slimey and I can scrape it off with my thumbnail. Could this be the dreaded cyano? or a different algae...couple spots growing on my powerhead also

Sounds to me like you might be seeing coraline growth. Is it just on the rocks and powerheads? Does start out like a little spot and then keeps getting larger? If your not finding it on the sandbed, good chance it's not cyano IMO. Also Cyano can just be rubbed off without using your thumb nail. As a matter of fact, when I had a bloom I was siphoning it off of stuff.

I have coraline that is very dark as you described.

I might be a little early in saying this, but CONGRATS!