How often do you calibrate your refractometer?

[RemoGaggi]

I got some calibration fluid last week and calibrated.  This morning, I checked it again with the fluid and it was off and had to recalibrate again.  I didn't use the refractometer all week.  Is it normal for it to get out of calibration just sitting?  Do you calibrate yours each time before checking your water?

[caas1496]

I have noticed the same thing with my refractometer and have got in the habit of calibrating before I use it.

[Clown79]

I check mine every week.

 

My calibration fluid that was a year old was off and I was calibrating weekly. Got new fluid and everything is back to normal.

[This guy is extra salty]

I check and calibrate mine daily

when I check my water parameters 

[banasophia]

Be sure to mix the calibration fluid before you use it

[Tamberav]

If you use a cheap refractometer...I would calibrate every time. I found my $100 to hold calibration but not the $20 ones. You get what you pay for but it's not like you can't just calibrate the cheap meter every time to save $. 

[jambon]

Where does a person get the fluid to calibrate a refractometer? I have heard distilled water will not work?

[seabass]

Well you can calibrate with distilled water.  However, that makes it accurate at a specific gravity of 1.000.  Some meters have a slope miscalibration, which causes larger errors the farther the reading gets from the calibration point.

Therefore, if your meter has a slope calibration error, using a fluid with a calibration point similar to your target specific gravity, will result in a more accurate reading.  However, if you find that your meter doesn't have such an error, you can get a good calibration by using distilled or RO/DI water.  You can check for slope calibration errors by calibrating with a calibration fluid, and then checking RO/DI water to see if it is 1.000.

 

http://reefkeeping.com/issues/2006-12/rhf/index.php

 

On 4/27/2019 at 10:21 AM, RemoGaggi said:

Do you calibrate yours each time before checking your water?

I use my refractometer to occasionally check my hydrometer.  I just find it easier to grab my hydrometer than to calibrate, test, and clean my refractometer.  So when I do use it, I calibrate it each time.

[Clown79]

2 hours ago, jambon said:

Where does a person get the fluid to calibrate a refractometer? I have heard distilled water will not work?

I order mine from online reef stores. I use brightwell calibration fluid

[xthunt]

Got a generic "atc" refractometer and it's always dead on whenever I check it with the cal fluid. Never lost its setting after I first calibrated it over a year ago when I first got the fluid (originally cal'd it with distilled). I handle it very gently, never shake it, and simply wipe it off with paper towel between uses. So maybe once a month or two months, just to be sure. 

 

Edit: Also I don't touch the metal part, or set the metal part on a hard surface that can draw heat away from it. When waiting for the temp to equalize I set it on junk mail, magazine, or folded paper towel.. whatever's on the counter at the time. 

[ef4life]

I recalibrate every day when I use it.

[banasophia]

15 hours ago, jambon said:

Where does a person get the fluid to calibrate a refractometer? I have heard distilled water will not work?

You should calibrate according to the instructions for your particular refractometer. Mine is a Milwaukee digital saltwater refractometer, and it is specifically supposed to be calibrated with distilled water. 

[Garf]

I calibrated mine with my RO/DI water last week. Can't tell you the last time I did it before then. It was off a bit, my tank was testing 1.025 before, and after calibration, 1.026. 

 

Reading about Slope miscalculation, I decided to get some calibration liquid, $12 at LFS. Turns out I can just use RO/DI, as the calibration fluid was spot on. 

[VictoryBell]

I calibrate mine every time I test my salinity. (Which is usually once or twice a week.) I'm a bit neurotic....