IMO, the best thing to do is not add all these things to try to take care of the problem, but instead you should take care of the problem at the source. Are you using tap, are you overfeeding, is your bioload to high? I thinkn you already are doing the best thing by starting to use RO water. You can do weekly water changes of 20% using RO water and that will drasticaly decrease your phosphates and nitrates. The fuge will also help. And all you have to do is manually pull out the hair algae and no new hair will grow because you are reducing the amount of nutrients athat you are supplying it with. But I would advise against adding a tangs, urchins, crabs just for the purpose of removing the hair algae. This will just add to your bioload and still wont solve the problem.