I read that if you lower the volume of sand in the filter it will work better as a pond filter. I only have 3 Koi, the rest comet. I don't need a biological componet to the filter as I have a homemade biological filter full of hyacinths and parrotts feather. All I need is a mechanical filter to take the solids out.
Sand Filters
I haven't heard of someone using a sand filter successfully on a pond, I've tried, it was not good. Sand filters for pools are not made to handle solids, they clog far too quickly. Also a sand filter needs quite a lot of pressure, a pool pump would be too expensive to run 24/7 and pond pumps are not made to operate behind so much pressure.