Planted Tank VIP
Join Date: Jul 2002
Location: Victoria,British Columbia, Canada
This sounds like beard or brush algae. Its a tough one to get rid of, but SAE's will eat it if you starve them for a few days.
This algae may show up as black, red, green, all kinds of colours and is very resilient. If you only have a little bit you can pluck it off by hand, but this sucks to do if you have a lot.