I love the set up gm333! I want to do the same thing when I set up my next tank. I do have lots of questions for you... I really not sure where to start.
-How big is your main tank? Is there a ratio to use for tank size/refugium size?
-Can you explain the water flow a little better for me? I seem to be a little confused.

Why does the water flow from the tank to the first and second sections in the 30 gal.? Why wouldn't you just have the water flow into the first chamber and then overflow to the next and so forth? As you can see I dont' know too much about the refugiums!
-Another basic question... Is you tank predrilled? And how does this work exactly? you just have a pipe that comes up from the bottom of your tank that sits above the sand?? Does the water just drain from the main tank down, or do you regulate it somehow?
-Do you need a light for the live rock?
I'll just start with these questions for now. Thanks!
-Nate