Instant Ocean Hydrometer
Hydrometers measure the salinity in a marine aquarium via specific gravity, The optimum salinity level is a specific gravity reading between 1.02 and 1.026 for nearly all saltwater aquariums. The Instant Ocean Hydrometer is the industry standard for affordable and accurate salinity measuring devices. The hydrometer is completely accurate when measuring saltwater between 68 and 85 degrees Fahrenheit.
The Instant Ocean Hydrometer is ready to use, just open the pack, dunk the Hydrometer in the water (you do not even have to get your hands wet) and take a reading. The scale is even color coded – fun!
If you don’t have one you need one – it will slip right into an order of live saltwater fish and coral. These are a necessity for brackish fish tanks too.