Refractometer

[horseplay]

So it looks simple but I need a lesson on this. Mine does not come with a manual (another way of saying even an idiot can use it).

The calibration fluid says 35 ppm at 77 degrees. It's kept at 65 degrees.

My room temperature in the basement is 65 degrees.

The tank temperature is 78 degrees.

The refractometer says ATC (I am guessing automatic temperature compensation).

Can someone please tell me how to calibrate and measure salinity?

 

[downbeach]

I usually start by cleaning the glass with some RO water, and drying it with a soft cloth/ paper towel. An ATC refractometer is designed to compensate for temperature, but you should allow your sample to sit for about 30 seconds before taking a reading. So, I'd place a few drops of the calibration solution on the glass, close the lid, making sure there are void area's and allow it to sit for 30 seconds. If needed, adjust the screw so it reads 35 ppt/1.0264. Clean it again, and check your tank and/or make up water to get your SG. I usually do my WC's about every two weeks, and check the calibration each time.