Well, as I came out of new tank cycle, I had the same problem! Hair algae EVERYWHERE!!! Since I only had one fish at the time, I did a MASSIVE (80-90%) water change. I took out every last rock and scrubbed them in a container of the old tank water. And I got a Cheveron Tang(which does the same thing as a Kole) I have since only gotten very minor growths of the hair algae, which I let grow just enough to be able to grab it when I pick it off the rock. I think the tang has helped a bit only in the sense that he is always grazing the rock and must get the stuff while it is still very small but he does not go after the larger pieces of hair algae. He does clean up the sand of diatoms if I don't feed him too much. ;D Just as stated above!