My marine set up has been running for 9 weeks and one of the rocks has started to grow really long dark red hairs - anyone know how to get rid of this or is it part of the cycling that will go on its own like the green hair algae did?
Take a look at this article. Are you using an RO/DI system? Perhaps overfeeding? Extended light cycles?
It may be time to start steping up to more frequent water changed and cutting back on your feeding a bit. When I had a cyano problem a combination of the two solved the issue.