Is the middle section a refugium? If that's the case, I'd consider changing the design so that:

1. The whole thing is much bigger
2. The tank drain/skimmer area is on one side, then the refugium is on the opposite side, and both those sections drain to a middle area where you have the return pump. You get water to the refugium by putting a tee in your tank drain and diverting some of the water to the refugium. There's a thread on the for sale forum about a 45 breeder for sale; if you look at the photo of the sump/refugium for that tank, you'll see exactly what I mean.

This has two advantages; it allow you to independently control the flow to the refugium and it sends tank water directly to the refugium, rather than skimmed water. Increasing the size, if possible, is important because you want a sizable refugium and a sizable return/evaporation area.