For me, Yellow Tang didn't do a thing for algae. Kole Tang scrubbed my tank free of algae in no time. Took him like one day in the tank to rid ALL the algae on the glass, rocks, and everything!!! :happyfish
Yellow Tangs can be pretty aggressive, you should add him last. Kole Tang aren't so aggressive so you should add him first. Your tank is large enough to keep them. Always QT first since you have a large tank and you'll have a lot of trouble catching them if they ever get sick... :happyfish