I am wanting to add 3 more tangs. How big of a tank do I need to upgrade to? Currently have a Blue Regal, Yellow, Sailfin, and Powder Blue. Really wanting to add a purple tang right now but I know that may not be a good Idea. All fish get along nicely. Current stock is the 4 tangs, Potter's and coral beauty angel. 4 clowns. 2 pajama cardinals. One yellow Goby. A fox face. And a Dottie back. Tank is getting along real good right now. I just looking for some advice.