Time to figure out a return pump for my new system. The tank is my living room, so ideally I would like to get it to be as quiet as possible. BRS was suggesting Sicce Syncra Silent 3.5, but I'm thinking maybe to go the DC route? The Reef Octopus Varios looks good, but not sure which one I need. How does one go about calculating required return flow rate? My stock pump is rated 660gph. Tank and stand height combined should be 4.5ft. So would a Varios 2 (792gph) be good? Some say that a pump lasts longer and is quieter if its not running at max.... so Varios 4 (1050gph)? Other suggestions are welcome. Thanks!