I had a hair algae issue in my old tank, I cut the lights down to 6-8 hours a day, then borrowed a lawnmower blenny from a buddy of mine (hit or miss on what kind of algae they will or won't eat). After he had consumed most of it, I did a huge water change, took him out and made sure I only fed an appropriate amount of food afterwards. Never had algae issues in that tank again.