Blake;

Mark Levin, I think is his name, has a website with several good sump/refugium designs. Over-under-over is the typical arrangement for bubble trap. Make sure you have a large area just before the return pump, otherwise you'll be evaporating water from that area REALLY fast, and could run your pump dry easily. Plus, after the baffles, if there's a nice big open area where the water slows down (water speed through a given chamber is inversly proportional to the volume) many of the bubbles will have time to rise to the top and burst. In your case, I'd leave a couple of feet (50-60 gal) after the last baffle. This is assuming you're pushing 1500-2000 gph through the 180. You'd still have 100 gallons of refugium space at least.