Fluval Sea Hydrometer
Fluval Sea Hydrometer provides an accurate and convenient method of measuring specific gravity and salt level in marine aquariums. Regular testing is strongly recommended as stable salinity levels are essential for the health of marine fish and invertebrates. It must be read underwater by attaching to the inside of the glass with the included suction cup or simply holding underwater during testing. It has large, easy-to-read markings with ideal salinity range clearly marked in green for clarity.