If you'll give me a quarter for every thread I can link where people have skimmers, do water changes and still have hair algae, I could retire.
If his skimmer was pulling out the nutrients then this thread would have never been born. If the he's not using a skimmer, then he's still in the same boat needing a cuc to help to break down the algae and other nutirents.
Part of setting up a tank is the cycle, the next part is letting it mature a bit and get stable. IMO this part entails enlisting a CUC, and then letting the other natural elements surface and take hold. This will include various species of pods, worms, snails, and an increase in bacteria population, things that will just pop up, or you can always add them.
If your really fond of the water change as being the answer I would do four days with no lights then a 100% change. Four days should be long enough to kill the algae, it will release it's nutirents and spores back into the tank, the 100% water change would almost all of them except those that settle into the rock.
It's not like there is stock that would be shocked be a large change. Even if you went this route, IME your still going to have algae problems down the road until the rest of the elements are stable and in place.
IMHO I have had better succsess taking things slow and letting the tank get nice and mature before stocking. When I setup my 65g I went two months with no fish or corals, and then another 3 months with just a bicolor blenny. Then I started stocking the tank. Stoked on the results. I go a bit slower then most, but I like the results I get.
JME