LMB's won't eat it past a certain length. And the type of hair algae is a BIG factor in getting anything to eat it. Standard hair algae wil be eaten by tangs, etc., but the other, described above as fernlike is called bryopsis. It is toxic to fish and inverts, so generally, they won't eat it. Lettuce Nudibranch's eat this as a primary part of their diet. I have two, and they do eat it, but not as fast as I was hoping. There really is no quick fix for hair algae. It takes some time to get rid of it.