Is this green hair algae?

[burgerchow]

The only thing that really works on hair algae is a seahare.
Snails and crabs, even fish, won't even put a dent into a hair algae infestation, but a seahare just mows it down. Once the algae is gone though, you need to pass the seahare along to another reefer, as it needs a lot of algae to eat or it quickly dies.

[subman]

It looks like bryopsis to me:
http://www.bostonreefers.org/forums/...51490-bryopsis
keep a close eye on it much harder to get rid of than hair algae as nothing eats it.

[gregzz4]

Have a look at the link subman posted
If your algae is feathery looking, then it's most likely bryopsis and you definitely want to remove it
If your's is soft and clumpy, it's turf
I have hermits that eat turf, but I'd need a huge army to keep it all down and I'm not interested in having that many