OK, to update, so what I did was to take a combination of your suggestions, and completely revised my original plan. Funny - you spend all that dime making lists and drawing diagrams, only to change the entire thing and spend only a few hours planning it...
Anyway, it turned out great. I removed the falls / bog from the middle of the pond. Put the small bog on the near side on top of the plant shelf that wasn't being used because it was too shallow, with the 700gph pump running a small fountain and bog filter.
The 950 pump also went in this end, but it runs the falls at the opposite far end of the pond. This falls is based in a pre-form liner bog sitting outside the pond. Instead of the natural rock falls I had planned on, I ended up with two small natural rocks, got a stone company to drill a hole through one of them (I gave up after 1.5 hours of straight drilling, over two nights), so I have a gurgling stone fountain in this bog. Then I ran the main output from the 950gph pump through a 2' long section of small concrete sewer pipe that I dug up in the old cemetery where I do volunteer work. Somehow it morphed from the natural look I planned into this quirky version, but it's cool, shoots out a lot of water for aeration and splash, and you gotta admit, it very unique.
I put the lilies at the near end with the 750gph pump, and they have about 1/3 of the pond. With no big fish at this end, I was able to remove the screen covers, so you can see the lilies nicely. The fish are seperated by a plastic fence, and it's holding them quite well. At first, I used the free sun screen a friend gave me, but right away realized it was too fine and might inhibit water being pulled to the pump and filter. So I tore it out and instead used a 1" plastic hardware cloth. Works great. I did have one koi jump the fence, and I had to remove all the heavy lilies to catch him, but that should not happen often.
The fish have the 10' or so at the far end of the pond, under the sewer falls. I have two milk crates stacked for shelter for them, with a few potted plants on top - taro, iris, umbrella plant. The idea is to keep this area uncluttered, and to keep the plants trimmed low, and remove and repot befoe they get too large.
So the koi have less length to swim in, but more width and clear square footage, plus it's easier to see them, too.
All in all, I'm pretty satisfied.
Took three or so days, over a week or so, including a fast run to the pond store because, of course, I misjudged the length of tubing needed and had to run for more, and a splicer part.
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