Thanks everyone.
Marcus, I have a 6000 GPH pump (was my only pump the first year) split into two hoses, one going to a 100 gallon skippy and the other hose going directly to the pool at the top of the falls. Then I added a second 2000 GPH pump last year with a hose going to the second 75 gallon skippy.
TMan, It is just a sheet of the pink insulation foam they sale at Home Depot. ($14 for a sheet that is 4' x 8' x 1.5"). I used a jig saw to cut the shape I wanted. Then used the jigsaw to cut some large holes that fit pots and some small holes for bare root plants. Eazy Peazy

The pink fades over time and actually looks a lot like the natural red rock we have here. I have creeping Jenny planted bare root in mine that covers the top in by summer time.