Snails seem to do the best job on hair algae for me. Depending on the strain, some fish won't touch it because it taste bad. RO/DI is important, mainly the RO, and a refugium can export extra nutrients. I have kept tangs in tanks as small as 30 gallons with no problems they don't grow all that fast, and I am not too concerned with the tang police....LOL.... As long as you take good care of the tang and feed it properly it can thrive just fine for a couple years. Some of the tang police kill them in 200 gallon tanks so go figure that. Anyway, turbo snails can also knock over your corals so you need to keep that in mind, as well as the perching fish killing spots on the corals.
Seriously, if it were my tank I would get one tang(purple or yellow) and about 15-20 snails. That is my preference though.