So I decided to up the size of the ball valves on the return pumps to minimize flow restriction. The 1" true union ball valves that I have been using are tiny inside! They actually reduce in size by about half from your standard internal 1" pipe diameter. So I measured the inside on a 1" pipe, and then the inside of a 1.5" true union ball valve, and the internal diameters were almost the same. The check valves also have a large interior diameter.
These 1.5" valves are frikin huge, but they will work well at not reducing the flow like the 1" would have.
Here is the interior comparison of a 1" to a 1.5"
