"There are several companies selling other Hanna instruments they indicate will test colloidal silver but were really designed to measure TDS (total dissolved solids). As calibrated from the factory the TDS meters will normally read only about one half the PPM of ionic silver that the PWT meter will read."
isn't it a bit funny that they talk about colloidal silver in the first part but then go on about ionic silver in the end. CS and IS are completely different things. I wonder why they said that.