return pump size?

[mark]

don't think I'd worry about wearing out my plumbing just too big is a waste of money (bigger the pump, higher the buck). What I would suggest is look into drain options for quiet tank such as a Herbie, but needs two bulkheads, (maybe consider use the 1.5 and one 1" for drains). On mine for the return I've pushed 2000gph through a single 1" line (now ~1000gph)

For flow through sump, see suggested no more than your gph of your skimmer, to as much as you can get without causing micro-bubbles returned to display.

RC headloss calculator might give ideas