With my pond I have a bottom drain (DIY), that flows into a settling chamber (DIY), pump then pumps the water into my skippy type filter (DIY), which is my water falls.
I then have a skimmer, flows into another chamber, then pumped through my UV, and back into the pond.
I will be adding another skippy filter / bog filter yet this year.
Here is my skippy filter. It is a 150 gallon stock tank, they have several different sizes. I then filled it with filter media, I used the power floor wax pads.
Here is my settling chamber: I used the liner from my old pond.
Here is the workings of my skimmer system:
My pond if 2 1/2 feet above ground. I did this to help keep my daughters out, and give me more volume with less digging. I am still in the "construction" stage. I started last fall. Now I just need to finish up the landscaping part.