your gonna wnat several chambers in your fuge, one where the water comes in and flows over to the actual fuge area, then another that the water, again has to flow over to get to a return pump that would then spit the water back to the sump or tank. if you can, i would plumb the fuge separately from the sump, that way the critters and things wont get skimmed out if you have the fuge first. threre are a ton of different options when settign up a fuge. do a search on all the forums for a diy refugium, and you should get a ton of nce pics/photos as to how to set one up! good luck
jon