Strange color all of sudden on rock

[coralfinatic]

Have 150g setup for over a year now. Everything fine, all live rock purpled up beautifully. all of a sudden noticing rusty red areas on some of my rocks. Is that just a sign of red algae or water chemistry issue?

 

[Aqua Pro Builder]

Have 150g setup for over a year now. Everything fine, all live rock purpled up beautifully. all of a sudden noticing rusty red areas on some of my rocks. Is that just a sign of red algae or water chemistry issue?

Hard to tell from this simple description. I think a CLEAR pic will help.

A rough guess would be sponge.

 

[Marteen]

Or maybe cyano?

 

[Avgou]

Without a picture I would guess a form of algae, from time to time I find small little coralline like deep red algae on my rocks...

I'm assuming it's very slow growing? Try seeing if you can blow it off with a turkey baster....