I have the Pondmaster skimmer/filter combo, it's been working great. The rectangular filter box rests on the bottom of the pond (I had to put some bricks on top of it to prevent it from floating), the skimmer is at the surface.

Newgen- how often do you need to clean the filter?

I've only had it for a month, still pretty clean. At the rate it's going, I'm guessing maybe every 6 months? Not sure. I'll just keep looking every month and decide.