Unless the pump is going to be used for some additional function, such as circulation through a filter or chiller etc, I would get a circulation pump and not a pressure rated pump such as the 100PX. That is assuming your sump is right below your tank. I also like a Pan World Pump as it is almost as good as an Iwaki. A little warmer to the touch and a little louder, but not extreme considering the 25 to 30% difference in price. I would choose the 50PX-X, which is rated 1110 gph at 90 watts. You might have to throttle down the flow just a little if you put in a really clean return piping system, but that does not happen very often. Figure on around 900 to 959 gph with a typical PVC pipe installation and 800 gph with a vinyl hose installation. For a clean PVC installation, thats talking straight cut pipe ends, deburred and double 45 degree fittings instead of 90 degree and true "Y" fittings instead of "T" fittings, and ball valves, unions, plus valves for balancing branch return lines if yoy used "T" fittings instead of true "Y" fittings. If will be a large enough pump to allow you to branch your return into two 3/4 inch or four 1/2 inch return nozzles which could pretty much eliminate your need for in tank obnoxious power heads. If you really want to get into it I can talk you through a whole system, with maximum flow and maximum return volume with medium velocities. Just in case you want to get heavily into corals rather than fish. :bounce: