I picked up a used RSM 130 recently as well. Upon further inspection, one of the return pumps puts out stronger flow than the other. As others have suggested, I'm keeping them in there for now and placing another powerhead on the right hand side. I'm not willing to dish out the cash for an MP10 right now, so I'm just going to put in a Koralia 2 that I have laying around for now. It will have plenty of flow to get the tank going, but of course, its not a Vortech. I plan on using the stock returns to keep my surface not looking like an oil slick, and directing them towards the water line. I'll use the Koralia for flow through the tank. Any powerhead will work, just make sure you get enough flow going through there.