glad to see your going with octopus skimmer instead of coralife, i have octopus skimmer and totally happy with performance, also have a euroreef on another tank. You still going to use powerheads for flow i don't think you will get enough flow using return pump for flow only i have mag 18 for my return and is not enough flow at all unless you use flow enductors, i don't like having to much flow through sump i have 1200gph going through my sump on my 125 gallon.