Zul i have had this as well I try get rid of it. It seems to get worse if I feed heavy with Mysis shrimp I agree with Ed & Rick pull it and cut back on Feeding with Mysis shrimp also test your tank for Phosphate.
Mike @ Amazon Bay sold me some sea hare's and they tend to eat mine and keep mine at bay for what its worth.
looks like a good start of hair algae. It is a nusaince. You really should get it out of the tank soon because with the right conditions it will multilply very fast on you. Emerald crabs will help, so will hermits and some tangs. None of my tangs would touch it, though I think it all depends on the individual tang.
Rick
Rick,
Nothing is eating the emerald crabs, hermits crabs and tangs. Can I put it in the refugium?
Zul