I am running 2 Poseiden pumps for returns, approx 1000gph ea at 4' head(
http://www.jlaquatics.com/product/wp...ater+Pump.html), dead quiet and I feel a little more comfortable having two return pumps in case of breakdown. They use 1" barb fittings making for quick set-up and you could easily reduce to fit your sea swirls. An alternative could be the Sequence Wahoo
http://www.jlaquatics.com/product/wp...550GPH%29.html it has 3/4" discharge and pushes 1500 gph
PS do you allready have your 180gal? I have my old tank 72x24x24 (11 months new) sitting in the carport I make for to be good deal for you! LMK