Here are my suggestions on how to get rid of hair algae,
1. Be sure you are using RO/DI water, and test it to be sure the filters are fresh.
2. If you do not have corals turn your lights completely off, (this will kill the algae).
3. Test your water for phosphates, the problem is if you have a lot of algae you may test 0 for phosphates and nitrates but it is because the algae is consuming these, when the algae naturally dies off it feeds new algae.
4. Do weekly %10 water changes, pull as much algae out as possible every day.
5. Run a phosphate sponge.
6. Be sure your bulbs are new and in the correct spectrum
7. Beef up your cleanup crew.
8. Set up a refugium with macro algae.
9. Run a protein skimmer
10. Dripping Kalk will help remove phosphates from the system
9. Once you get rid of the algae, keep Ca in the proper levels and coralline will grow and the hair algae usually doesn't grow where there is coralline.
HTH- Carla