patience...
I have been running a 10 gallon for only 3 months, and ran into your problem last month, even though my cleanup crew is pretty good. I helped them by manually removing a lot of the hair algea. Now I am getting a lot of coralline algea, which keeps my rock from having surface for the hair algea, so it's under control. A matter of ageing the tank, I guess... I have gone through red algea (Chemi-Clean fixed that), brown algea (water changes), green hair algea (manual removal) and green bloom (3 days of total darkness). My tank is not totally clean, but I feel like it's getting better every day I fight... (plus my snails need something to eat!) Now, if I just find the balance of iodine, iron, trace elements and plankton that will keep my coral growing while not turning my water into a nutritious broth for algea, I will have won the battle!