Instant Ocean Testing Hydrometer for Aquariums

The world’s marine waters have a salinity between 32 and 35 parts per thousand. Brackish water, by definition, must be lower than the lowest value of this range. Many freshwater aquarium species can withstand (or benefit from, according to some) a certain level of salinity in their tank water. Calculating the salinity of water is done by measuring specific gravity (SG) with a hydrometer, or alternatively, conductivity via a meter. Both of these methods are temperature dependent – readings vary with the warmth of the water. For practical purposes, brackish aquarium water should range between 1.002 to 1.022 SG at a temperature of 77 degrees Fahrenheit. Most brackish aquarium fish can tolerate this range. A 50/50 mix of fresh and marine water would provide a salinity of 1.012 SG – a happy medium for a general brackish aquarium.

The hydrometer doesn't take into account the water temperature. It will read the salinity and specific gravity accurately at temperatures between 68 and 85 degrees Fahrenheit.

The lowest reading is 0 - 1.000. The Hydrometer is normally used for saltwater tanks so it has higher level readings, depending on how high the brackish level is it may not work. At this time we don't carry refractometers.