I thought we had numbers from the tests, but I do not see a sheet with test results now. The water softener lowered the calcium carbonate concentration some, but in the sales/technician's opinion, was already good enough without treatment. I see numbers from 1990 with the original owner's tests, and they had more calcium carbonate then.
I wonder how the impurities affected the softener is as I let the salt level in the brine tank drop, and the fraction of the black stuff rose. It was very nasty looking, and very opaque with only 1/4" of water!