DIY Refractometer Calibration Fluid help

Mhoover1481 · Oct 9, 2024

New to Reef2Reef, I hope I’m doing this right!
I am having salinity issues after being in the hobby for about a year now.
My refractometer’s (new and old) are reading wonky. And I have calibrated with 35ppt solution from BRS and AccuraSea, different readings from Both and NOT 35 ppt.

I am reading up on Randy Holmes diy solution using NaCl and purified water.

I have the tools and supplies to make this solution, but I’m trying to understand the science.

In theory, if I do his recipe, the NaCl fluid reading should be 1.3394 on the refractometer, and that equates to 35 ppt seawater, right?

So, I should make his calibration fluid, put it on the refractometer, if it says 1.3394 ish, I should calibrate my refractometer to 35ppt and then I should be getting accurate readings?

I’m having some trouble understanding

Thanks!

Randy Holmes-Farley · Oct 10, 2024

Most hobby refractometers do not have a refractive index scale on them, but if it does, yes, do that. If not, then calibrate it to read 35 ppt or sg = 1.0264. All are equally suitable.

Mhoover1481 · Oct 10, 2024

Randy Holmes-Farley said:
Most hobby refractometers do not have a refractive index scale on them, but if it does, yes, do that. If not, then calibrate it to read 35 ppt or sg = 1.0264. All are equally suitable.

Okay awesome! So in conclusion, (if) I created the solution exactly as stated in your article, I should be good to drop it on the refractometer and calibrate straight to 1.0264 or 35ppt and assume it’s accurate or very close?

Thanks again Randy, I’m so thankful for your help and insight!

Randy Holmes-Farley · Oct 10, 2024

Mhoover1481 said:
Okay awesome! So in conclusion, (if) I created the solution exactly as stated in your article, I should be good to drop it on the refractometer and calibrate straight to 1.0264 or 35ppt and assume it’s accurate or very close?

Thanks again Randy, I’m so thankful for your help and insight!

Yes, that’s its intended use.