Tuesday Tech Tips - How to Calibrate your Salinity Refractometer

A salinity refractometer is a handy device that allows you to quickly check the salinity of your aquarium water or salt water mix. To be sure your refractometer is providing accurate readings, it is best to calibrate it. Here's a quick tip on how to calibrate a salinity refractometer.

American Marine Pinpoint Calibration SolutionFirst you need a salinity calibration solution, such as this one from American Marine. This is a salinity fluid that has been lab tested and proven to be at a specific gravity as stated on the bottle. Using a clean pipette or eye dropper, take a sample of the calibration fluid and place it on the surface of the prism, just as you would when testing your tank water.

Salinity RefractometerNext, take a look at the reading in the meter. If it is above or below the salinity stated on the bottle of calibration fluid, then you need to adjust your refractometer. Using the small screw driver that came with your refractometer, turn the calibration screw to the left or right until the meter reading shows the exact salinity that is stated on the bottle of the calibration solution.

It's that simple! A quick tip, always be sure to calibrate your salinity refractometer to the desired range that you are testing for. In other words, do not use RO/DI water to calibrate your refractometer to ZERO.... you are not testing for zero. The ideal range is generally a salinity calibration fluid of 1.026 or 35%.