As Mike said, if you can remove the rock from the tank remove as much algae by hand as possible. In the tank you have problems. Removing it in the tank spreads the algae faster.
Your tank has an issue that needs to be addressed first.
Hair algae is a sure sign of excess nutrient and or bad bulbs.
I'll explain the bulbs first as it is easiest. Your bulbs lose their spectrum over time. Algae grows best at the 6,500K or lower spectrum. Bulbs fade at about the one year mark. At this point algae grows faster than anything else in the tank. This reduces usable nutrient for coral and or fish. They feed less and grow slower. This frees up the nutrients for the algae to grow in and now have the perfect light spectrum to flourish. Under powering can do this as well. If you don't have enough light any coral or photosynthetic organisms will not grow, this stagnated life form leads to the same as above, excess nutrients and perfect conditions for algae.
Next you have either way to high a bioload, feed way to much, don't have proper flow or filtration.
1. physically remove rock from water and scrub clean. Quick rinse in clean salt water in another bucket. After each rinse, replace this water so as not to contaminate rocks dipped later.
2. add more flow to the main tank. Algae tends to grow slower in high flow situations.
3. get a better skimmer.
4. feed less.
5. turn off lights for 3 days out of each week until algae recedes. You must do a significant water change when turning the lights back on. This removes the phosphates and nitrates created from the algae that died. Other wise you just end up feeding the remaining algae.
6. significant water changes every few days. You must remove the algaes food source. This is generally measured as phosphate. Nitrates can add to the problem.
7. run lots of carbon. replace weekly.
8. set up a phosban reactor and follow directions. When treating for existing problem you must toss out the media weekly until the problem clears up.
9. A uv sterilizer will not clear up the problem but will help prevent the spread of algae any further while attempts are made to clear away the problem.
10. more clean up critters. Some of the smaller hermits (such as blue legged hermits), snails (such as turbo snails), and sea hares will mow right through algae. I'd recommend you get your hands on a lot of turbos, maybe about 3 per gallon if possible. Use them to eat the algae and then resell them when the problem recedes.
Buy a phosphate test kit. Preferably a Tunze brand kit. They are the most accurate that are easy to get ahold of. The ones they sell at most every LFS or super center just are not accurate enough to figure out when the phos is under control. Most read as 0,2,4, etc.. The Tunze read from 0.01, 0.02, 0.03 etc...