I built the little shed for the filters out of pallets, in fact the base was a pallet. The basic design consists of 2 pumps in mid pond. One feeds the larger tank which is a black systern cold water tank, so i could cut my own inlets & otlets exactly where i wanted them. That filter consists of 3 layers of foam.(course to fine grade), with plastic modules in the lower half, then straight out to pond. This filter is kept on all winter, but in the summer i had this on a timer so it was off at night, making less noise.
The other pump feeds a uv filter in the side of the "shed", & then up into a top sprinkler fed smaller filter with foam & plastc modules ,& then 2 paralel outlets back to the pond.
Originally i had the small filter with the uv but the water went green. What was happening was that the uv was doing it's job of clogging the stuff together but the pump couldn't cope with dragging it up to the filter, but as soon as i added the other pump & filter it was clear as a bell in days.
So if you have a small filter & a uv & your pond is not clear,---
1---fill a plastic clear pop bottle with your pond water, 2 ---if the muck settles to the bottom of the bottle, your uv is working ok, you just need something else to drag it out as i did.
Any queries on anyting please don't hesitate to email me.