Does anyone have instructions for this tester? I have had mine for two years and can’t find the instructions.

Not sure if website links are allowed, but here is the link to the PDF manual. http://hmdigital.com/wp-content/uploads/2016/11/ap1manual.pdf

which conversion factor does this meter use to convert EC to ppm 500 or 700?

The website says 0.5 NACL which leads me to believe its 500. I think 700 measures a different solid other than nacl.

can you use this to check colliodal silver ppm???

Yes, I use it for that purpose. I really like this tester. It is accurate when compared to another meter I have that has been calibrated for reading silver levels. If you are going to purchase this meter I would suggest adding a TDS Calibration Solution as well.

ASIN	B007KDYOMU
Item model number	HMDAP1
Manufacturer	HM Digital
Product Dimensions	14.99 x 1.27 x 2.79 cm; 80 g

HM Digital - HMDAP1 AP-1 AquaPro Water Quality Total Dissolved Solids r, 0-5000 ppm TDS Range, 1 ppm Resolution, +/- 2% Readout Accuracy (Magnetic Body)

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