I was thinking about a calfo that isn't quite coast to coast, but maybe 24-36" in the middle of the tank with a bean overflow. However, I was thinking, if the overflow plumbing is in the middle of a 6' tank, how would I adjust/maintain it if this tank was backed up against the wall? I could just as easily move the overflow to one side, but then how effective would that be...might as well make it coast to coast? To those of you with calfos, how are yours plumbed? I am also curious to see how tanks with a coast to coast run their return if the entire back of the tank is utilized as an overflow.