replying to homerlex, Shane wrote:
TDS meters work by measuring conductivity. They do not measure exactly the
number of disolved solids in parts per million as suggested. They actually
measure the conductivity of the water and that is translated to an approximate
TDS. Some dissolved solids are more conductive than others. Sodium is more
conductive than calcium. Therefor water is more conductive after a water
softener than it is before it, causing the TDS meter to register a higher
number.

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