True Seawater Refractometer - D-D The Aquarium Solution

The D-D True Seawater Refractometer is purpose-built for reef aquariums, measuring salinity and specific gravity with precision. Unlike standard brine refractometers, it's calibrated specifically for natural seawater's refractive index—accounting for magnesium, calcium, and other ions that affect accuracy. Key features include auto temperature compensation (ATC) for ambient conditions between 10–30°C, a 0–40ppt scale offering 2.5× greater resolution than conventional 0–100 scales, and a copper body that responds quickly to temperature shifts. Calibrate at 20°C for optimal results. Ideal for serious hobbyists and professionals maintaining stable salinity in reef systems.