haha bb7551.... I still wouldn't recommend u getting a powder blue tang. I never liked the idea of keeping fish just for a while and then sending it away... it's life were dealing with. But neways....
The problem will be the tangs probably will fight. The pb tang needs alot of room and is quite territorial. The yellow tang doesn't need as much room but is even more territorial... meaning it's territory is a smaller space but is more aggressive about it.
The next problem is ur tanks immaturity, it wouldn't be wise to add such a delicate fish to a new tank... by new i mean anything below a year to a year and a half. srry guy but just my oppiniones.
well neways, wish u luck