Is it normal to have to recalibrate your refractometer every day?

[aerotiy]

I tested my salinity the other day before going to the LFS to get my water tested. It read at 1.025 and then the LFS told me it was 1.023 using a digital refractometer. I’ve been using the handheld one and thought that it didn’t need to be calibrated that often but the past few tests I’ve been checking with refractometer calibration solution before I test my water and the refractometer is off every single time even if I had just calibrated it the day before. Anyone know what could be causing it? I got this one from bulk reef supply for $40

[Oldsalt01]

Could be temperature variations. Are you letting the sample sit for 30 secs or so, before you take a reading?

[Boggers]

Temp and be sure to clean off the end after use. If it is still changing that often you might consider a replacement.

[SaltyBuddha]

Most refractometers need to be calibrated at 68 degrees F. Buy some 35ppt solution, get your apartment/house to 68 degrees and give your refractometer time to adjust to that temp. Then calibrate it at that temperature.

 

Your refractometer has a built in temperature adjustment meant to work when calibrated at 68F. If you calibrated it at a higher or lower temperature than 68F, your results will be off when taking measurements at different temps.

[aerotiy]

Yes I let it sit for 45 seconds before reading like the instructions say. And my apartment is always at 76° to save money, are you saying it has to be at 68° every time I want to take a reading? Because then I don’t know what to do  I can’t afford that

[Clown79]

I check mine every 2 weeks and it's spot on every time. I have had to calibrate it twice.

[SaltyBuddha]

33 minutes ago, aerotiy said:

Yes I let it sit for 45 seconds before reading like the instructions say. And my apartment is always at 76° to save money, are you saying it has to be at 68° every time I want to take a reading? Because then I don’t know what to do  I can’t afford that

 

Nope. You just need to calibrate it at 68F. After that, the ATS will adjust accordingly at any normal temperature when taking a reading. Some people put the refractometer in a sealed bag, then in a bucket with water at 68F if you don't want to run the AC.

 

Most good refractometers will say 20/20 to designate the temperature for calibration.

20C = 68F

 

There are a few out there that are 25 and calibrate at 25C (77F) but MOST are 20C. You can check what your says on the display to confirm.

 

[Clown79]

Mine automatically adjusts to read salinity at any temp between 10-30 degrees 

[aerotiy]

Thanks everyone. I’ll have to do the 68° water trick for my next calibration and hopefully it’ll stay set for a while. 

[Martin Riggs]

15 hours ago, Clown79 said:

Mine automatically adjusts to read salinity at any temp between 10-30 degrees 

 

This is what I’ve been doing. I have a Milwaukee unit and it has a temp sensor and I try to match room with tank temp. Every time I do a reading I clean the lens with distilled water. Read it, zero it out then wipe. Take my reading from tank water than clean again. 

[Tamberav]

I use the old style Milwaukee one (before they went digital) and it is always spot on. Too bad they don't sell it anymore. I really think the quality of refractometers varies.

 

[Clown79]

Mine automatically adjusts. I use a large drop of tank water, give it a few seconds, take my reading. Done. Clean with water and dry.

 

Every time I check with cal fluid, it's been spot on. I've had to calibrate only a few times

 

I don't use digital

 

Each refractometer is different. Even digital doesn't mean it will be 100% accurate.

[Tamberav]

Let us know if the 68 degrees thing fixes it, I believe they are supposed to come calibrated to that already but sounds like yours didn't or got out of wack.

[aerotiy]

I will! I’ve been working a lot so haven’t had time to do it yet but I will this weekend. Thanks

[MockandRoll]

The Milwaukee digital refractometer is the way to go if you can. One of my best purchases.