With the Silver Puppy It's more accurate to measure using a conductivity meter in microsiemens or uS. The uS reading happens to be close to the actual PPM with silver ions. TDS meters are designed for a broad spectrum of minerals.
The meters measure ionic more accurately than the colloidal type contained in Meso silver.
I don't notice any bitter taste with my Silver Puppy (using the Magnetic stirrer) but others often complain. Could be just an individual preference.