lawnmower blennies love hair algae, and all types for that matter....perfectly reef safe. Blue hermits, Scarlet hermits, and Astrea snails are some others that will help drastically..I just got past a bad hair algae outbreat with these, and a couple of turbo snails as well for my 55 gal. If you only have fish in the tank and no corals, after add the cleanup crew mentioned above you can leave the lights off for a few days and cover the tank so its in complete darkness....it's what I had to do....plus a big water change using ro/di water instead of tap water, tap water is by no means any good for saltwater tanks period...hope this helps!