Is this (good) algae?

[jeremyg]

I have a fish-only tank with artifical decorations, that require manual cleaning every month or two. After 1-2 weeks they begin to slowly get covered in this stuff - I'm just wondering what it is and if it is considered good or bad? It also grows on the edge of the overflow box, and on the powerheads.

 

[mangus]

Does the algae in question brush off easily or is there a chance it is Coraline?

 

[jeremyg]

I'm not really sure what Coraline algae feels like. Is it hard? This stuff is soft.

It washes off, but takes a little bit of agitation.

 

[mangus]

I'm not really sure what Coraline algae feels like. Is it hard? This stuff is soft.

It washes off, but takes a little bit of agitation.

Yes, Coraline algae is hard but it flakes off. Maybe it is red slime algae or some type of Cyanobacteria?