Refractometer & Hydrometer Calibration Standard, Accurate Reference for The Calibration of Seawater Refractometers, Hydrometers & Other Density Measuring Equipment (RES250)

If you are using a refractometer you need to calibrate/verify it from time to time. This solution makes it very easy to to do. Just a couple of drops and you are good to go.

Cannot determine accuracy, but results are consistent when solution is shaken well.

Good calibration solution, works exactly how it's supposed to.

This product does what is on the tin, but is packaged with a childproof cap that cannot be used as the neck and top of the bottle collapse while pushing down to open it...it's f'ing saltwater there is no reason for a childproof cap especially one as poorly designed as this.

This product is terrible. Crashed my tank thinking my refractometer was wrong. When really this calibration fluid is horrible.