Too much flow??? Never enough!!! All of my problems have been tied to not enough flow. I'd say go for two mp40's if it's in the budget, seriously. The mp40's will give you a higher volume flow than the MP10, and you can just turn the speed down. The 40 breeder is a great tank, but it's pretty wide. The mp40 would be much better to cover the width of the tank than an MP10