Tips for less frequent calibrations of refractometer?

[ReefsandGeeks]

I have been trying to check my salinity more often in an effort to see the day to day fluctuation, or even the fluctuation during the day. I have calibration fluid for my refractometer, and I use the calibration fluid before each measurement. It seems my refractometer drifts by as much as 3ppT after a day or couple of days. Once I calibrate it, the meter seems good, but then the next day when I use it it needs adjusted again. Are there any tips or tricks to reduce the drift on the refractometers? or do I just have to deal with it and calibrate/adjust with each and every use? Even if I could get it to go a week in between calibrations it would make taking measurements more convenient.

 

[JWClark]

Interesting. Is it temperature compensated (say ATC on it)? I only calibrate when I think about it and am only 1ppt off when I do. However, I am gentle and never shake or bump the unit--ant it is temp compensated. Would imagine jostling of the unit would require more frequent calibration.

 

[dieselkeeper]

I use the digital refractometer. You calibrate every time you use it. Turn it on, a couple drops of RO water, hit calibrate, absorbs the RO water with paper towel, a couple drops of tank water, hit read, done. No more making sure the water stays put, or searching for good light. I will never go back. You can catch them on sale. Got mine for $75.

 

[ca1ore]

That's odd. My refractometer is rock solid - cannot actually recall the last time I calibrated it. I do also run the Apex salinity module and probe, so I have a reference should my refractometer drift. BTW, it is quite easy to leave a bit of residue on the refractometer face that will skew the reading. I typically test a sample 3-4 times before believing the reading.

 

[billdogg]

That's odd. My refractometer is rock solid - cannot actually recall the last time I calibrated it. I do also run the Apex salinity module and probe, so I have a reference should my refractometer drift. BTW, it is quite easy to leave a bit of residue on the refractometer face that will skew the reading. I typically test a sample 3-4 times before believing the reading.

^^^What he said^^^

I'm sure I have a bottle of calibration solution someplace in the fish room, but it's been long enough that it would take me a few minutes to find it.

 

[hkgar]

I had one that was also rock solid, Check it from time to time and it never vried. I broke it and thought I ordered the same one but is black and not blue and I calibrate it everytime I use it.

 

[ktownhero]

I use the digital refractometer. You calibrate every time you use it. Turn it on, a couple drops of RO water, hit calibrate, absorbs the RO water with paper towel, a couple drops of tank water, hit read, done. No more making sure the water stays put, or searching for good light. I will never go back. You can catch them on sale. Got mine for $75.

I have a Milwaukee digital and I rarely calibrate it. It stays dead-on all the time, as far as I can tell. Every once in a while (like months) I'll do the calibration and it's perfect.

 

[solitude127]

my tip for less frequent calibrations of refractometer....... get a better refractometer. I've been using a VeeGee refractometer for the past 6 years and each time I calibrate, it's always pretty close.

 

[outssider]

I would calibrate before every use. When you consider the cost of 2 drops of calibration fluid, it would be stupid/lazy not to. That being said, even if your unit says ATC it's really not. Some refractometers are very sensitive to room temperature (the temperature of the refractometer itself). If you were to calibrate at room temperature of say 70 degrees in the morning and check it again in the late afternoon when the room is 80 degrees, i'll bet you see a point or two difference in the reading. also the light source can make a difference.

 

[billdogg]

^^^What he said^^^

I'm sure I have a bottle of calibration solution someplace in the fish room, but it's been long enough that it would take me a few minutes to find it.

This will be seen as blasphemy, but when I do want to check it, I compare it to my 3 30 year old swing arm hydrometers. They never vary at all from what they were calibrated to.

 

[thegrun]

You might try tightening the bezel ring that is around the adjustment screw just a little.

 

[Ron Reefman]

+1 for what billdogg said

I found my refractometer needed adjusting every 18 to 24 months. Not a big deal.

But I compared my cheap hydrometer to the calibrated refractometer and the difference was 0.004. So I put a label on the hydrometer that says "add 0.004". It's now 6 years later and my hydrometer, which I use all the time, still is 0.004 too low.

People talk about hydrometers like they are junk and refractometers are the gold standard. I'll take a calibrated hydrometer any day!

 

[ericarenee]

+1 for what billdogg said

I found my refractometer needed adjusting every 18 to 24 months. Not a big deal.

But I compared my cheap hydrometer to the calibrated refractometer and the difference was 0.004. So I put a label on the hydrometer that says "add 0.004". It's now 6 years later and my hydrometer, which I use all the time, still is 0.004 too low.

People talk about hydrometers like they are junk and refractometers are the gold standard. I'll take a calibrated hydrometer any day!

10000+ my Refractometer is in the drawer of Misfit hardware that is just NOT NEEDED But to costly to throw away...
:beer:

 

[DasCamel]

Know thy instrument... little things cleaning the glass make all the difference. Anyway, I calibrated when I first got it and check every few months. Nothing ever changes. Boring really.

 

[A sea K]

I think I have checked mine once in 10 years. Guess what I'll be doing later today.

 

[OceansMotion]

Ive heard of many people having issues about that. However they are all using cheap refractometers that dont compensate for temp. Id recommend getting a sybon refractometer. Its high quality and adjusts for temp. I would only calibrate every month or so and rarely it would be off at all. Also keeping it clean by rinsing with rodi and a cleaning cloth like the ones used for glasses goes a long way to keeping everything where it should be.

Sent from my LGLS775 using Tapatalk

 

[A sea K]

OK so I checked mine again and it is spot on. FWIW the box says it's an RHS-10ATC, not an expensive model at the time of purchase and I've had it since I set up my 210 over 10 years ago. I typically use my old reliable hydrometer but will use the refractometer occasionally to ensure the hydrometer is still in check. It is stored in the same cabinet as my 15 gal top off container so it is exposed to some humidity not to mention I live in a very humid area to start with. Anyway it gets thoroughly rinsed with RO/DI water after every use and patted dry then left out to air dry before being returned to its storage case inside the cabinet. Been doing it this way for years and as I recall when I did check it last time it did not need any recalibration then either.

 

[d2mini]

I have been trying to check my salinity more often in an effort to see the day to day fluctuation, or even the fluctuation during the day. I have calibration fluid for my refractometer, and I use the calibration fluid before each measurement. It seems my refractometer drifts by as much as 3ppT after a day or couple of days. Once I calibrate it, the meter seems good, but then the next day when I use it it needs adjusted again. Are there any tips or tricks to reduce the drift on the refractometers? or do I just have to deal with it and calibrate/adjust with each and every use? Even if I could get it to go a week in between calibrations it would make taking measurements more convenient.

The only one I've known to shift is the Red Sea one.
And their instructions say to use RO water to calibrate.
Takes just a few seconds to calibrate it at each use.
But can be annoying nonetheless.

 

[A sea K]

The only one I've known to shift is the Red Sea one.
And their instructions say to use RO water to calibrate.
Takes just a few seconds to calibrate it at each use.
But can be annoying nonetheless.

I was reading my instructions yesterday to see if it listed a brand name and also for calibration instruction, the instruction on mine also state to use RO water to calibrate but I check mine with 35ppm calibration fluid and it was right on the mark.

 

[Heuristic]

I'm sitting at 6 months using the same refractometer and I just tested it this weekend to make sure it is still accurate and it is still spot on.