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Making your own TDS meter calibration fluid

759 Views 3 Replies 3 Participants Last post by  Darkblade48
Hello all.

I have a TDS meter and I would like to calibrate it so I can verifiy my 4dkh drop checker solution. I want the tds meter to be as close as possible to the actual result. Normally I wouldn't bother calibrating it because I'm usually only interested in TDS deltas rather than the true figure.

My NaCl calibration fluid has mostly evaporated leaving inaccurate results. I need to get more, but I don't want to pay for it. I have aquarium salt and Morton's table salt. Using aquarium salt, or deionized seems to be the way to go. I have a gram scale and 50 mL graduated cylinder to make the solution.

Now just going over this in my head, since the TDS meter reads both positive and negatively charged ions, 1 mg of NaCl in 1L of water should raise the TDS by this correct?

so if I add 500mg of NaCl to 1L of water the TDS should be 500?
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· Administrator
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Since TDS is a measurement of ions in water, adding sodium chloride to 1L of water would give you a reading of 1000 mg/L.

Or there abouts. Conductivity isn't the best way to measure TDS, but is reasonably accurate for inorganic salts.
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