I run a 1/4hp pump. We used to have a little bigger but I only need 1 diffuser anymore to help clear the bigger end that we swim in. The fish get the rest.
This is the pump I run, the company is somewhat local to me in michigan so that's why I went with them.
Bubble Pro Mini Sub-Surface Aerator | Scott Aerator
Outdoor Water Fountains, Pond Water Features, Fountain Pumps, Kits and Supplies from Scott Aerator | Scott Aerator
www.scottaerator.com