I have dual return/drains and run mag 9.5 & 7 and my water stays between 76 & 78 always. Thinking about power consumption I prob should scrap the 7 and put a mp10 in there,,decisions decisions.
I just built my own sump/refugium and found that keeping my return lines and skimmer as far apart as possible made a pretty clean return pump section.
Also, did you say you were gonna build this,,how do you plan on sealing those baffles your putting in. Silicone gun will never fit. where are the sponges going, if any. Where in the pic was the dual reactor? where is the intake anmd return on that?