I have a multicontroller ( and a single controller I am not using) and the 6000 and 6100 units. I have two Sea Swirls (1/2") for the returns. The Sea Swirls are on either side of the back wall of my tank. A Mag 12 powers that return. The tank is a standard 120 at 48X24x24. How should I situate the two Tunze units? Is there a prior thread on this you could direct me to?