Hagen Aquarium Hydrometer - Thermometer - 12 in.

Proper salt content is vital to the health and well being of captive marine species. Use the Hagen Aquarium Hydrometer to determine actual specific gravity of marine water aquariums on an ongoing basis. Ensure all replacement water has the same salinity as the aquarium.
TYPE FLOATING
AQUARIUM TYPE SALT WATER
Float the Hydrometer in a quiet area of the aquarium free of currents or turbulence. Alternately, place a sample of aquarium water in a clean glass or jar that is deep enough to float the hydrometer freely within. Specific gravity is determined by reading the line in the unit closest to the water surface. Read the thermometer to ensure the water temperature is safely in range for your marine inhabitatnts. The Hydrometer will float higher in more saline water and lower in fresher water. Surface tensiion creates a meniscus that should be ignored when taking a reading. Use the actual water surface level, not the highest point the water reaches on the exposed tube.