• Calibration, TDS Meter, and Refractometer

  • Jeremy

Good afternoon! I have a refractometer and a TDS meter, but I encountered a problem with their calibration. As far as I know, the refractometer is calibrated using reverse osmosis water, preferably after ion exchange resin. To do this accurately, I need a calibrated TDS meter to ensure that it shows 000 TDS after the resin. But how can I accurately calibrate the TDS meter then? It seems like a closed loop. I'm not sure if my reverse osmosis system outputs 000 after the resin, so how can I accurately calibrate the TDS meter to then confidently calibrate the refractometer?

Bonnie

Take TWO TDS meters As a rule, they come calibrated from the factory, so to ensure the accuracy of the readings, measure sequentially with both devices. If the readings are the same, everything is fine. In any case, TDS meters rarely have such a margin of error that could negatively affect the calibration of the refractometer. If you have serious doubts, after calibration, compare the readings of your refractometer with any other refractometer/areometer, or check the readings on a pharmacy isotonic saline solution, for example... (0.9% NaCl)

Wendy

In an isotonic saline solution, for example... (0.9% NaCl), should it show 000 on the TDS meter? What should I do if I don't have another TDS meter and refractometer for comparison of readings?

Maria

no, of course TDS shows conductivity, i.e. the presence of free ions of salts in the solution; it will show zero in distilled water. I meant to check the refractometer on saline solution (if they haven't diluted it at least).

Gregory9432

I see, so the refractometer needs to be calibrated to 0 with the saline solution, and then it will show the correct readings?

Shane

No)) Then it will definitely show incorrectly. We check the TDS, osmolate/distill to zero - if everything is okay, we calibrate the refractometer to zero. Saline solution is needed to verify the accuracy of the refractometer readings - if you have doubts about its reliability!! (since we already know the percentage of salt content in the solution) But I wouldn't worry too much, I would just check the aquarium water, and for control, I would use a hydrometer (float). This is definitely available in any store and with any marine aquarium enthusiast.

Alexandra

Guys, what do you think about this calibration solution? As I understand it, if you put a TDS meter in it, you need to adjust it to a reading of 1000 ppm, and then voilà, the TDS meter is calibrated, right? Has anyone used this liquid?

Joseph8592

What should be displayed on the reflectometer for the saline solution??? What parameters????

Andrea6761

for 110, for TDS calibration? I highly doubt it... 0.9% is 9 parts per thousand SALINITY... (to be precise, it should be 0.89 percent, or 8.9 parts per thousand)

Tami

I have a scale on the refractometer from 1000 on the left and in percentages from 1 on the right, so how should I adjust it to show almost 1% or 1000 not at the very zero, did I understand correctly?

Jenny

This is not "a thousand" and not percentages! marked with a red line (readings of the refractometer on the correct isotonic saline solution)

Bethany

If I calibrate the refractometer this way, my readings will be 1040 today.

Bonnie

I think this is unrealistic; probably 0.9 to 1% should be set.

Angela7060

What exactly is confusing you? The right scale in the provided illustration is for PROMILLE (there are no percentages on the refractometer!!), the left one is for SPECIFIC GRAVITY (not density!! Density is shown by the hydrometer). 1 promille = 1/1000 1 percent = 1/100 Thus, 0.1% = 1 promille The red line is exactly at the level of 8.9 promille in the illustration, or 0.89% salinity. Yes - and this is not a calibration solution, but a CONTROL solution (to check the accuracy of the readings). Calibration instructions are all written for DISTILLATE!

Anne

Besides you, there are 3 more sailors in Zhytomyr, all you need to do is write in a private message, call, or come over. If you don't trust your osmolality meter, I can offer purified water from a pharmaceutical factory for calibration (there's definitely a complete zero there).

Emily3506

Today we calibrated with Nikolai, the TDS meter showed an error of 0.03, the reflectometer seems to be fine now.