Jamie, I've used 2 different refugium's in my set ups.
1 - had a 30gallon long which was gravity fed into my 42 hex. The water was pumped up to the fuge by a minijet and the fuge was lit by a LOA fixture from HD. Very slow turnover. My thoughts were that this would allow the algae plenty of time to absorb nutrients. Tank was drilled for a bulkhead and returned back to the display, no need for a standpipe as the flow was so slow that the noise was negligible. To me, this is definitely the way to go... gravity fed, slow turnover, 24 hr photoperiod.
2 - now I use a 100gallon stock tank for a sump/refuge. The thirty is plumbed into the 42 and now houses zoas. The refugium has a couple hundred pounds of sand and 30# +/- LR. I like the additional volume, but I definitely prefer the gravity fed system of old to establish/maintain pods. The macro does it's job and, through all of my other struggles, my NO2, NO3, PO4 are all undetectable using Salifert test kits.
Garrett.