Thank you all for the input! Today me and my son start digging, and after discussing it think that a small bog is the way to go. We're going to start out with feeding it via the 16" waterfall box and see how that works out. Once the pond is up and running, I may opt to install pipes below the surface and move the waterfall to another location for more circulation in the pond. Will post some progress pics!
Not sure what you are describing, but just to make sure, here's a quick bog filter explanation...
Distribution manifold pipes are laid in the bottom of the bog which are covered with about 12" of pea gravel. The pipes have a series of slits cut in them throughout their length.
The water gets pumped from the pond through the slits in the pipes. The water rises up through the gravel and returns to the pond by way of natural flow.
I'm not sure if this is what you meant, but just checking.
You don't want to do the opposite. What I mean is you don't want to pour the water on top of the gravel, letting it seep down and return to the pond. That would result in a layer of stinky muck covering your gravel.
I got worried when you said "feeding it via the 16" waterfall box".