I have used quite a bit less filtration volume than you recomend though I think more is better, I have sometimes added ugfs, but usually go with a boxed sponge prefilter, a container of biomedia like bioballs or lava rock, and a trough that is fed from the bottom so that the water rises through more biomedia and into an area of water hyacynth or water lettuce. the water is returned through either a gravity fed splash chute or pumped through spray bars or both. I do use multiple set ups and pumps on larger set ups. the largest pond I set up was in Navato , California and was just under 4 meters wide x 8 meters long x 1 1/3 meters deep and was mainly an aboveground pond but set into the ground by 1'2 meter. Not counting the pre-filters the filter system contained about 15% of the total volume. The pond was shaded from direct sun by a suspended canopy made of shade mesh and contained potted water lilies, lotus, and cattails. The fish were bluegill, 2 big largemouth bass, several good sized channel cats, a striped bass, some big yellow suckers, a couple of terrapins, and a bunch of gambusia and some crayfish, the latter two were replaced as needed. When last I saw it the pond had been running well for over a year. the bioload was low compared to most koi ponds that I have seen, less than 35 kilos of livestock in a pond of about 35000 liters.