the return pump depends on what size drain you have. If it's 1'' then a mag 7 pushing up 4ft will work fine. You always want the retun pump to push the same or a touch less than the overflow can handle. That's what I have on my 125 except my overflow is a hob
type. 600gph overflow with a mag 7 return pump. A skimmer is not a must, but healthy pwc
's or if you are a diy'er, an algae turf scrubber. After reading about them and with Mr.x's and Floyds r Turbo's help, that's what I run and it works fine. Plus, it will be cheaper than a skimmer to acquire.