im a owner of the model 3 proflex sump and man this sump is dead quite. i really like it a lot but the one thing i dont like is the salt creep you get on top where the top is for the fuge. other then that i love it; no micro bubbles, dead silent, and a decent size. just dont go any smaller then the model 3. if you can get the model 4.
now if you really want a bad a** sump check out "my reef creations" sumps. good luck