I have a 72 bow, and can only fit a 12" sump (front to back), and have already decided to buy either an ETSS 500 or 600, or an Aquac EV 120 or 180. I just need to build the sump to fit one of these skimmers. I would like a refugium, but am waiting for more feedback as to bioball&skimmer vs Ref&skimmer before I spend any more $$$. But I will check it out, just in case.