Thank you sir. The cement is so strong that you can pick up the structure by the span without the cement failing. However, the rock can fail. I had to use cyanoacrylate to repair it.
Sump is unconventional in that water flows in a U shaped path into a high velocity, turbulent run where dosing and top off will be added, then to the return pump. Water does not go over the baffle, but around it. I sort of enjoyed working with acrylic. Wife not a fan of the snow-like shavings.