If you are speaking of the brown algae that is starting to cover all the rock and even the glass, this is not a hair algae. It is a diatomaceous (silica) algae that is common in new tanks. A Yellow Tang is usually not the best and most Tangs do not touch it. If left alone it should go away on it's own, usually within a month, but it's pretty ugly till then.
The best organisms for this kind of algae control are snails. Turbo snails are not the best grazer for the money. Mexican (Margarita) snails and Astrea snails are best. If you really want some large turbo snails because your tank is large, just get a few and see how they do. The other snail that is good is the Cerith. The Cerith Snail shell is what our hermit crabs live in. Cerith's are good for disturbing the top 1/2 inch layer of sand. Better in my opinion than a sand sifting star because they eat only algae and leave the rest of the microfauna alone and don't go so deep into the sand bed.
Speaking of microfauna (small invertebrates) Julian's newest book on algae control mentions the real value of these little critters. (I'm positive that this book will be a hit in the WMAS Library) "Microverts" can be major algae eaters if we let them. So long as we don't put damsels, wrasses, Mandarin Gobies and other meat eaters in the tank until much later. Give the microfauna a chance to get established and it's population to be large enough to eat the algae before it's visible to our eyes.
If we add a lot of snails and hermits (try 2 snails & 1 hermit/gallon) at the time when the brown algae is starting to cover everything, they will help until the microfauna population is sufficient. Then remove the CRABS as we start to see them getting too hungry. We can tell when they don't have enough to eat because the algae problem is over and they are fighting over bits of uneaten food or even fighting to eat the snails. The extra snails can be removed at about this point or later when we see them eating what little bit of coralline algae we have on our new live rock. Sometimes they sart scraping all color (actually algae) off the rock, down to the white.
The best places to get hermits and snails are The Pet Factory and Mountain Shadow Marine (Fish-4-U might match the prices for WMAS members). TPF has small hermits which are excellent at $0.40 (Astrea snails $0.60) and MSM has the best selection of a variety of snails and larger hermits for $1.00 each.
Bring extra snails and hermits back to the store for credit or bring them to the WMAS meeting to sell or give to friends.
Be sure to start some macroalgae like Caulerpa in your new tank too.
We are starting a booklet of answers to common questions for all levels of hobbyist. This may become available online as it develops.
Please ask more questions
Mark - WMAS founding member, past President and current Treasurer