Take "GroTheory "brand TDS meter out of box. I bought it off Amazon. It was highly rated. Put it in the solution HM Digital 1000ppm TDS Calibration Solution It reads 1300. Retested after rinsing and drying probes but same result.
Reset it? Replace batteries? Heard you need to stir probe in solution.
The seller contacted the factory in China I'm my behalf:
"Hi Scott, Thank you for your reply. The factory replied that if the TRS Meter displays about 1000, it is relatively standard, but if the TRS Meter is bought and placed for more than 1-2 days, there will be an error in the value. If you meet any thing, you can contact us at any time. Best regard! "
I think something got lost in translation.