dB,
Putting a fish or anything else in your tank that will eat the hair algae is putting a band-aid on the problem. What you need to do is to solve the problem. What worked for me was to stop feeding the fish so much food and to add a clean up crew. I still feed the fish once a day, just not as much food. Also the clean up crew, mainly of red hermit crabs, will eat the stuff on the bottom of the tank. This stuff on the bottom of the tank turns into nitrates that the hair algae uses for food.
Scott