Wow that’s a huge huge dropThat is currently my only hypothesis - going from 2.1 to 0.3. I didn’t do it all at once, here is timeline:
July 26 - 2.1ppm
Aug 1 - 1.6ppm
Aug 2 - 1.48ppm
Aug 8 - 1.0ppm
Aug 16 - 0.6ppm
Today - 0.3ppm
So dropped about 1.8ppm in a little over a month.