Not to cause trouble or anything, I actually disagree with your design. At least if you plan on pushing a lot of flow through that system. As most folks know, refugiums shouldn't have a significant amount of flow, as compared to a standard sump, that is handling the skimmer and other filtration (sans refuge). It is actually better to setup your refugium like this:
Intake | Return | Refugium
& Skimmer | |
Then, on your return coming from the tank, split the flow so that about 20% goes through the refugium side and the other 80% just goes through the basic filtering (skimmer, etc). I have valves setup so I can actually adjust the flow, depending on how the system responds. You may actually end up doing 40% through the refugium, etc. It just depends. Regardless, with this setup you don't have to worry about high flow volume causing problems for your refugium. I've seen some folks with so much flow, the refugium get blasted and isn't really doing much.
In any case, just thought I'd throw in what I found out through my own experience (i started off with a refugium exactly like the one you designed).
Cheers,