Red Sea’s Refractometer’s read the absolute salinity of saltwater at 25°C / 77°F (the general reef temperature), so there is no need for temperature compensation.These highly accurate instruments are specifically designed for the ionic content of natural seawater, providing a more accurate salinity measurement. The Display:The easy-to-read, higher resolution display is focused to the relevant range for reef aquariums up to 40ppt and includes an integrated Automatic Temperature Compensation (ATC) for accurate measurement at standard ambient temperature.The PPT scale on the display is calculated using an algorithm for seawater and will therefore give a reading of the Absolute Salinity. ATC – Automatic Temperature Compensation:Temperature is probably the biggest cause of incorrect readings with a refractometer. Calibration and testing of water samples should generally be done after the refractometer and water sample have equalized at the correct temperature.Automatic temperature compensation (ATC) compensates for a few degrees of difference between the ambient temperature and the calibrated temperature of the refractometer. Larger temperature variations will give an error of approximately 1.0ppt in the salinity reading.ATC does not adjust the PPT reading of a refractometer to the temperature of the aquarium.
