What scale 500 or 700

Does anyone know what scale a i spring tds meter is?

I looked for an answer online and I couldn’t find any info at all. I’d say you can use a calibration fluid to help figure it out.


@jdw Here is a conversion chart someone had posted on here that I use. Hope this helps

. From Perfect Grower.

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What’s the difference between ppm500 and ppm700 scale?

  • The ppm 700 scale is based on measuring the KCl or potassium chloride content of a solution.
  • The ppm 500 is based on measuring the NaCl or sodium chloride content of a solution.
  • The ppm 500 scale is also referred to as TDS - total dissolved solids.

700 is the 1.

I believe i figured it out ! On the back of the meter it said measuring NaCI so i guess it’s 500 scale. @Pet_de_Chien @Deepsix @Cap_Ron @beachglass a big thanks to everyone!!


Well heck. I been doing 700 all along.
go figure

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700 scale I believe is usually used out of states countries ect. Usually from what I’ve seen in like Africa Australia ect. They do have them here but usually it’s read on the 500 scale here in states