Washing My Tesla

[42M3]

Water softeners are ion exchange resins which trade hard ions calcium for soft sodium. Might be less prone to spotting.

Sadly it will still spot. It will just be different minerals, and I’m sure NaCl or KCl build up, however small, isn’t any better for your paint or other parts.

 

[Yelobird]

It is the minerals, you need deionized water to avoid it. The equipment runs about $400 from CR or diy for less, and the consumeables (cartridges) about $150/pair. This gets my softened well water down to 0ppm for about 300 gallons or $.50/gal.
You’d get more or less gallons depending on your water hardness. A PPM meter is about $15.

Are you sure about that? For homes or other you use RO water (reverse osmosis) to remove TDS. DI is not suggesting and Especially not down to 0 ppm because at that point it is acidic. DI is used in EDM machinery to erode metal. RO set to 50 or less PPM is recommended for spot free and safe rinse and drink.

 

[Genie]

I use this system: DIW-20 High Output Wall Mounted Spot Free Wash System - Deionized Water Maker

I may have some terminology wrong but it takes my well water from about 95ppm at the softener to 0ppm at the spigot. I don’t have a gallons meter but estimate I get ~300 before the TDS gets to 1ppm and cartridge replacement Is due.
it’s not a cheap way to wash but you don’t get spots. I don’t know anything about how that would change the pH, maybe I’ll try some test strips.