Noob question, which PPM scale?

Good morning, afternoon or evening :wink: Some on here mentioned that I should not add nutes until the PPM gets at or below 1000ppm but now that I have a blue lab tester I’m noticing several parallel scales, so which is it that is being referred to? I have PPM 500 and 700 on my tester along with a couple others.
I’m at 100 for the 500 and 1200 (I think) on the 700.
Thanks !

You want to use 500 scale for most of your readings. A PH of 900 in veg and 1,100 to 1,200 in flower will work fine.

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The scale used often depends on the scale used by the nutrient line.
Many of us use Jack’s 321 - Jack’s is user friendly and supplies info for all three major scales

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