I was wondering if your system has a bypass or might be able to add one and fill your pond back up to capacity that way.
No bypass. It's also the absolute lowest point in the neighborhood. I'm pretty sure it's the runoff basin for the neighborhood that the original owner turned into a pond. It predates the geothermal. The basin would have been built in 1994, the geo was installed in 2012, and the pond was stocked sometime before 2007 (according to the previous owner).
