Calibrating Refractometer

I've been using distilled water to calibrate my Refractometer, assuming that the water should read 0.

Is this okay?

 

It won't be accurate, maybe 3 points off.
PINPOINT® Salinity Calibration Fluid - English

 

Yes it will be close enough, its the way its been done for years. I trust distilled or RO/DI water more than I do a homemade calibration solution which some recommend. How do you check that your calibration solution is accurate?

 

Is it 3 point higher or lower?

If you know it's 3points higher it could still be used for calibration.



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so i guess the best calibration solution is distilled???
or RO/DI from the grocerystore...

 

Sorry but thats bull, I have used both and one right after another and there was absolutely no difference. I have used both "calibration" fluids, American Marine, Aqua Craft Products and they both said exactly the same as the gallon of distiled water I used to fill "ACE in the HOLE" battery in the basement.

 

I agree distilled should work.

I happen to placing an order with foster & smith this weekend, added some calibration fluid, so I'll test both and post the results.

 

Refractometers and Salinity Measurement by Randy Holmes-Farley - Reefkeeping.com

 

Ok did my own test and here's the scoop.
Used a reference liquid from fosters and smith, read 35ppt perfect.
Used distiller water and it read 0ppt.
So distilled water works fine no need to spend $8 on calibration fluid.

DarkHorseMBA

 

Distilled water can be used. However, you need to used a pipette that has been cleaned well (or preferably an new one that has never been used in saltwater). The glass and plastic lid needs to have been wiped with distilled water as well. Then you need to allow the water sample to remain on the lense for 10~20 seconds to adjust for temperature.

At the store I use Distilled Water and a pipette that has never been in anything other than distilled when I have weekends when I had my customers come in to get their refracts calibrated. End result....I've found that I've had to adjust about 80% of their refracts. (However, they weren't off by a lot. Additionally, a consistent salinity/specific gravity is more important to me than an actual number).

I have seen a bunch of refracts get different results when switching from 53 mS fluids and distilled. A lot of it is going to depend on the accuracy of your refractometer. A lot of people have the cheap Chinese RHS-10ATC model. There are 4 models all sold under that model number (I have no idea why) and some are better than others.