I'll tell you what you can do get some hermit crabs, urchin and snails. You can also shorten the light cycle, you can even turn the lights off for 2-3 days and black out the glass for that matter the coral will be ok for a short duration black out. They should be good for more than 1 week. If the hair algae is just starting you should be able to nip it in the bit now.
So after 2-3 days lights out you need to pluck off any algae you can see or you can use boiling water and a turkey baster pull out the rock with HA and do spot hot watering it will kill the algae and anything the hot water touches so where the corals are don't do this method. But any where else is ok as you will keep the rock alive and get rid of the HA. When basting the rock tilt it so the water runs off in the most direct way this is to keep as much of the rock alive as possible and do it over a container or some thing not the tank, it works and you will get rid of the HA.
I did this to the rocks in my kids tank to get ride of a different type of algae and it worked really good I was able to save all the feather dusters even the hard tub ones. also when you do start turning on the lights again have some cheato in the tank as it will eat up the phosphates quicker than hair algae.
Once you start turning the lights back on keep it on a shorten light cycle for quite awhile it will help let the urchin and crabs and snails do there job. The urchin does the best job only eats algae and it picks it off so it is down to the bare rock they may eat some of the coralline algae but that will grow back.
One thing once the algae is gone move the urchin to a different tank or give him away or he will keep eating the coralline algae and he will eat it faster than it will grow.
You can keep all animals above as permanent residents in your tank if you like they are all good cleanup crew.


Bill