You
could install a water softener, but the payback period from saved vinegar, detergent, and energy would probably be ~60,000 years.
I wouldn't put vinegar in the filter. I have no idea how long its effectiveness would last or whether it might degrade the media, as RH77 noted. I'd just use a polyphosphate filter and clean the condensor with vinegar on the rare occasions it is needed.
- LostCause