3 weeks (or so) ago I did what the books say not to do and got a yellow tang abou 2 weeks after getting a purple tang. The purple immediately started beating up the yellow. About a week and a half ago I caught the purple tang and he's living in the sump (I've put some rock etc in there). How long do you think I should keep him there before reintroducing him to the main tank (which I've changed around a bit) with the yellow in it?