Hmm, could be similar to the evil red fuzz that I had. It never got out of hand for me (and never grew on anything since the tank is new)...
Is it like the furry red spots in this pic? If so, my blue legged hermit devoured it overnight, but there was only a few scattered areas with it. He also ate the burgundy velvet stuff that was growing on the rocks (it wasn't cyano, it was some other kind of algae).