I think it is best to set both pumps at 58.
Here is my math:
I turned everything off except 1 pump (set to 70), and then watched as the Seperator water level rose.
It rose at about 0.17 per 15 seconds.
Next I turned off everything except the water seperator.
the water level decreased at 0.28 per 15 seconds.
therefore it would be optimal for both water pumps to produce (0.28/2 = 0.14) per 15 seconds.
14/17 = 82.25%
82.25% * 70 = 58 (70 is the original setting 58 is optimized.)
Notes:
1. it's good to let the water level get to 5 or 6 first, so that if a pump fails you have a reserve.
2. the reason for doing this is because when the water hits 10, the pumps shut off. if the pumps shut off they do no turn back on, and will eventually cascade into a system wide power down.