I like the look of your patio. Do you find your feet catching the tops of the river rock sometimes? I did a similar thing for a walk that also doubles as a deck drain. I have river rock in other places and even knew of the potential 'catch' issue but I built it anyway and tried leaving the steppers a bit high, However I still catch them once in while.View attachment 158376
Every now and then I kick one haha on accident, but over all it worked out better than we thought. That river rock will surround the pool, so in the end everything will look uniform and like it was all built together.