Sump and Refugium Design

Matt just completed building a sump and refugium for their tank and has offered to help me out with this one. Here is the design we came up with. The in-flow chamber from the display tank will flow over a large pile of live rock rubble. The refugium will contain a sand bed, maybe some more rubble, but mostly it will have macro algae and red mangrove. The macro algae helps control the growth of nuissance algae in the main display tank. The last chamber will have the protein skimmer and return pump. If we do it right, this last chamber should hold about 5 gallons which will make doing water changes much easier. The sump and refugium should add around 15 to 20 more gallons to the total volume depending on where the water level ends up. The last chamber needs to also be able to hold all of the back-flow water if/when the pump is turned off. The return to the display tank will alternate left and right by using a SCWD device. And there may be another powerhead added to the upper right corner in order to provide adequate circulation.