Right, but do u believe this process would elevate the tds ppm and thats why it was 450? Now its reading closer to 100-125. Ordered new tds pen but this one is new too!!
test your tds pen in calibration fluid. if the pen checks ok you can trust it on the water ppm. if you are running dwc / rdwc you should invest in good brand name ph and ec pens.
a few things can affect tap water quality. most common is a break or work somewhere else in the line, not just changes at the source.