" this PWT meter will read Colloidal Silver directly in ppm by applying a correction factor....We supply instructions with the proper correction factor so you will be able to easily calculate your PPM" http://www.silvergen.com/ppm_meter.htm
Please let me know what they say when you call them.
They did not supply you with the correction factor. That factor is available only from Silvergen, not from Hanna Instruments.