Calibrating refractometer

WhiskeyCoffee · Nov 14, 2016

I just opened up my new refractometer and out of the box it's saying my RO/DI water has 0ppt / 1.0 SG and my tank has 1.027 SG. Should I even bother trying to calibrate this? Some of the Amazon reviews state they took it straight to the LFS to test and theirs were already calibrated...

R33FLIF3 · Nov 14, 2016

yes you need to calibrate your refractometer closer to a usable range! once calibrated you will notice your di water is off from 0ppm

WhiskeyCoffee · Nov 14, 2016

Bump #reefsquad

saltyfilmfolks · Nov 14, 2016

temperature effects calibration. the lfs is nuts.
Heres Randy.
http://reefkeeping.com/issues/2006-12/rhf/

jsker · Nov 14, 2016

Yes I took mine to the fish store to check mine against there and found mine was off. We determined that I need a better refractometer, but what I do is know were there is reading and where mine is reading and I check my water to that. I have a controller and just double check to make sure.

jsker · Nov 14, 2016

R33FLIF3 said:
yes you need to calibrate your refractometer closer to a usable range! once calibrated you will notice your di water is off from 0ppm

Good answer

Brew12 · Nov 14, 2016

WhiskeyCoffee said:
I just opened up my new refractometer and out of the box it's saying my RO/DI water has 0ppt / 1.0 SG and my tank has 1.027 SG. Should I even bother trying to calibrate this? Some of the Amazon reviews state they took it straight to the LFS to test and theirs were already calibrated...

In my opinion, calibrating it with RO/DI to zero is better than nothing. Better yet is to create your own calibration standard as Randy describes in this article.
Just remember, this is the recipe for a refractometer. It will not read accurately in a hydrometer.

http://reefkeeping.com/issues/2004-06/rhf/index.php

R33FLIF3 · Nov 14, 2016

get this calibrate monthly..
http://www.bulkreefsupply.com/aqua-craft-refractometer-calibration-fluid.html

john.m.cole3 · Nov 14, 2016

most of em now that I have seen say ATC on them. Stands for automatic temperature controlled. @Brew12 beat me to recommending Randy's recipe for calibration fluid. I calibrate mine every time I use it FWIW.

joeyrm7 · Nov 14, 2016

you can buy calibration fluid at BRS I do mine every 2 weeks

WhiskeyCoffee · Nov 19, 2016

I bought calibration fluid on Amazon for $11 and guess what - my refractometer was spot on 1.026.

john.m.cole3 · Nov 19, 2016

Hey, that's awesome. I used my refractometer for 4 months before buying calibration fluid.I couldn't keep any corals alive bc my SG was 1.020

. Now I check with calibration fluid every week. It will hold its accuracy as long as you don't drop your refractometer or shake it really hard.

Ty Hamatake · Nov 19, 2016

From what I've heard, calibrating with RODI water can cause problems with accuracy. Due to the fact that you are calibrating it to the lowest end of the spectrum possible, any variance is going to have a much larger effect the higher your SG goes. If you think of it as a graph starting at 0, a one degree variance would be negligible. The higher up the graph you go though the bigger your discrepancy gets. I use the calibration fluid from BRS. Calibrating your refractometer to a value much closer (1.026) to what you are testing for results in less chance for error. Just my 2 cents