Just bought a pump plan on reinventing my fish closet that is in the master bedroom behind the tank. I have a 55 gallon tank and a 10 gallon tank. The ten gallon fits in the 55 gallon. On the left side of the 55 gallon the water will drain into the filter sock, some carbon and skimmer section. I want to place the ten gallon on stilts if you will inside the 55 gallon tank. The return pump ( External ) requires a 2" bulkhead all the way on the right side of the tank. No way for me to put the pump in the middle section for a gravity feed. So I plan on splitting the drain with a valve to feed the fuge then the other main drain on full blast. The water will flow under the fuge to the return. The water from the fuge will just trickle over the sides of the ten gallon tank. Then I want to add an ATO to the system. I have a reservoir barrel chiller and phosban reactor that needs to fit in this equation as well. Plus I want to leave room for a new skimmer hopefully. I have a berlin turbo skimmer now had it for 11 years. The pump is a Reef Flo Dart, I also have an RO system only a 4 stage just RO no DI.