What scale is my PPM Meter?

Hey guys,

Sorry if this is a really dumb question. So I’ve been testing my PPM on my first grow and when I told my local hydro store guy what my PPM Meter read (769PPM) he asked what scale it is? Apparently different Meters use different scales (500 Scale & 700 Scale). I didn’t even realise! :flushed:

So I’ve tried to find out which scale mine is and I can’t find that info anywhere! It’s just a cheap EBay Meter with very little info. I’m wondering if any of you might know what it is or how I might find that out?

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EC-to-TDS Conversion Factor: NaCl (avg. 0.5)

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I have a meter that is very similar I bought from Amazon
It’s a dual scale 0-900 it reads to .100 ppm accuracy
From 900 to 9999 it reads to 10. Ppm Accuracy


I didn’t know this , very interesting.


Thanks to all of you for your responses :slight_smile: