I have 4 pre filters on my pond...mag 5, mag 7, mag 12 and a mag 18 all running various items such as two fountains, a uv sterilizer and an external biological filter.

With that said I absolutely hate the way I have it all setup. Two of the prefilter pumps are impossible to reach without getting into the pond and they all are a pain to have to continually clean once every couple of weeks due to light clogging....but if I want maximum performance on the pumps I have to do it.

I would definitely recommend a surface skimmer because I hate netting the pond morning and night!

I'm actually turning my current 1000gallon pond back into a crystal clear fountain...because it's directly in the sun and the green concrete pond does not look nice especially since it's painted blue.

My new pond will be a preformed pond on the back patio. It's covered and will be on a concrete slab.

Good luck.