Brack Calc

Brack Calc is a useful and easy to use application designed to help users measure the waters salinity, concentration and temperature. Knowing the salinity is important because each fish species has a range of salinities within which is comfortable. In most cases, this range is very narrow, but among species that inhabit brackish waters the range is much broader.
Brackish water contains salt at a concentration between 0.5 and 30 parts per thousand (ppt). Though the saltiness of the sea varies, most seas have a salt concentration of about 35 parts per thousand. Notable exceptions include the Baltic (where the saltiness is less) and the Red Sea (where the saltiness is higher).
To use Brack Calc most effectively, find out the temperature and the specific gravity of your aquarium. In most cases, the temperature will be 25··�··�C, the default setting for this application. Use a hydrometer or a refractometer to measure the specific gravity. Moving the sliders to the appropriate values on the window will give you a precise salinity reading.
For most brackish water fishes, a salinity of 15 ppt is adequate. Species such as green spotted puffers, monos, scats, and common archerfish will be happy at this salinity. Salt-tolerant freshwater fish, such as kribensis and Australian rainbowfish, should not be exposed to a salinity above 5 ppt. Brackish-tolerant marine fish, on the other hand, such as eel catfish, dog-faced puffers, and batfish, will need a salinity between 15 and 30 ppt.