Not sure what you are talking about. Overflows? You would want to use a bean animal style. It has 3 drains and it is the safest and quietest. i personally like the Ghost or the Shadow overflows myself. They are thin, so the tank sticks out less from the wall. The other option is using internal overflows, they allow the tank to be all the way against the wall, but they also create dead spots and take up valuable real estate inside of the tank. If you are going custom built tank, I'd look into a built in external overflow that goes coast to coast.