DIY refracometer calibration regent???

skinz78 · Jul 28, 2012

I just dropped my refractometer and I know it threw it off a bit because I checked the SG right before and it was 1.022 and now it is 1.019. I remember there was a way to DIY refractometer calibration regent, anyone know how to do it?

Clay4AU · Jul 28, 2012

distilled water should read 0

dsmhero · Jul 28, 2012

My D-D refrac says to use RO/DI water. I do not see why this wouldn't work.

skinz78 · Jul 28, 2012

Some time ago I was told not to rely on 0 sg water?

dsmhero · Jul 28, 2012

Here is my instructions just for reference.

[url]http://www.theaquariumsolution.com/files/SEAWATER%20REFRACTOMETER%20V2.pdf

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Cyber-Burn · Jul 28, 2012

I think this is what you were looking for Skinz. I only calibrate with a 35 ppt solution, which is best, especially if you do not have a refractometer manufactured specifically for saltwater use (such as a salt refractometer).

Here are the instructions for the DIY calibration solution. I have not persionally used this, I always have used the commercial 35 ppt calibration solution, but it should work:
Reef Aquarium Salinity: Homemade Calibration Standards by Randy Holmes-Farley - Reefkeeping.com

skinz78 · Jul 28, 2012

Ahh yep that's it, thanks!

reef life · Jul 28, 2012

I have the calibration solution also. Make sure you shake it before using. I found that out from reading a recent post from young einstien (I think that was his r2r name) It will make a difference in calibrating your refractometer.

mcarroll · Jul 29, 2012

I can understand in theory at least that calibrating the device to the measurement you expect to get (35ppt standard vs 0 ppt RODI) should give you the most accurate reading, but...

I'd like to hear others' experiences, but I've compared calibrating with 35ppt standard to calibrating with regular tap water and RODI water and I really couldn't see more than a half-point or so of difference between calibration with the standard and the other two - insignificant IMO. This was a standard refrac like you'd see for sale in any LFS - nothing fancy. For our purposes is there a real gain by using the standard?

-Matt

specvjeff · Jul 29, 2012

I've been using rodi water to calibrate refractometers for many years with no troubles at all.

Cyber-Burn · Jul 29, 2012

It really depends on the type of refractometer it is. If it is a refractometer that is made specifically for saltwater then it usually won't matter, but several of the refractometer are actually made for simple salt solutions and are not for saltwater, and that is where you run into the bigger differences. As for calibrating it to a known source of 35 ppt then you know that a reading of 35 ppt is acuratate. Whereas if you calibrate to DI water which "should" read 0 then you have a much larger margin of error between 0 and 35 ppt. Our DI water is also not standardized, so we can only make an inference that it is at 0 ppt.

turfster26 · Jul 29, 2012

For the life of me I do not know why more people do not simply spend the $6 on calibration solution? Just about everyone sells it and it takes all the guess work out of a DIY solution. Our tanks are worth so much money in corals, etc that 6 will not break the bank. I've had mince for over 3-years and still half full.

JMHO.......