return pump suggestions?

[DJ88]

I'd say Mag 9 or there abouts. If you are planning on a rubbermaid sump then that is pretty much your option. A pump you can submerge that is. If you can, get a glass tank, have some baffles made and have the pump mounted externally. Mag 7's and 9's add about 2-3 degrees to tank temp when in sump. If you went external I'd say another option for reliability is a pump in the MD series.

Plus this will let you run your skimmer pump in the sump. Speaking of which. make sure your skimmer pump is in an area in the sump that has a constant level of water. If it fluctuates with evaporation your skimmer will not always be dialed in. it will change how high the foam goes etc due to the change in water pressure on the pump intake.