If you have an excellent amount of circulation with just the return pump to start, it's doable, although I wouldn't personally advise it. In order to make 2 MP10's work in a 120, you'd really have to run them at full power. Honestly, you'd be better off buying one MP40. I own both the MP10 and 40 models and I personally think the 40 is a great investment and really puts out a lot more power. Later on you could then add a second MP and go with the 10 or another 40. They're pricey, but worth it.