I will try some too, Based on Randys remarks, it is not completely regenerated, or at least only the color change happened. I'm guessing, that it's not nearly as effective, and/or will exhaust even faster now.
being high co2 well water, hard to imagine it exhausting faster. I get only 100 gallons product water per anion cartridge. I was thinking of upgrading to a 20" cartridge so it would last longer between changes. Also, I modded up a co2 degasser setup, both the PVC pipe style and later on a barrel with air stones. This surprisingly did not seem to prolong di cartridge life. So I was beginning to think it wasn't co2 after all, but maybe sulfates, chlorides, nitrates or silica. So I ordered a ICP test for my post RO water, and did not indicate much of these baddies. In the end Co2 rules the day it seems