I set up a system for a client of mine that has a 600 gallon display tank in his office. The sump is a 240 gallon tank. I installed a 100 gallon long refugium, 55 gallon RDSB, and a 75 gallon frag tank connected all to the main system. The QT is a separate 55 gallon tank used for copper dosing and hypo treatments.
The Frag tank is drilled on the back, it has one main water line coming from a T off of one of the main pumps. The water is then drained from the tank and back down into the main 240 gallon sump.
I put in two hydor koralia 4's for extra water circulation. To also make a copepod and extra filtration grounds, I have approximately 50lbs of live rock and 25lbs of live rock rubble which I occasionally attach a frag from the main tank on. (He does most of the work.) As for lighting, there are two 250 watt MH's on 4 hour timers (14k) and two actinic 110watt 4ft VHO's.
I also have a 100 gallon salt mixing tank for water changes and extra water just incase.
The guy went a little crazy with his setup, but I was glad to do it for him! I will post pictures after awhile. Really busy right now.