My new Koi pond is 24 ft long and 8 feet across at its widest point. It is 4 1/2 feet deep in the middle. The pond is natural (no liner). It was built two months ago and is spring fed. Roughly 200 gallons of water runs through the spill way each day. The bottom and sides are clay and I put six inches of limestone gravel on the bottom. At this point, I have no filters, pumps, or a water fall. I live in Northern Minnesota and have a decent size budget for this project. I have not decided whether to keep the pond open in the winter. I have several questions since I have no expertise.

The far wall (see picture) is 3 feet above the water level. How wide should the weir be at the top of the waterfall? Should it just plunge straight down? I have tons of natural rocks (see picture); should the face of the falls be natural rocks?

Filter/Skimmers - What should I have? I have read so much but am very confused. Should I buy a waterfall weir with a filter? What type of skimmer? Do I need a pressure filter? What about the bead filters? Should I have a UV filter?

Pump - Can whatever system I design be serviced by one large pump? What pump would you recommend?

System design - I realize I am asking for help designing a system...are there any DYI resources available?

One final question - if I decide not to keep the pond open in the winter (it gets below zero very often here) can it be designed so the take down in the fall wouldn't be much work?
I appreciate any feedback on my question.

Attached Images
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