The salt content of our marine can be given in different values. We strive for a value of 35 per thousand as salinity. This value can be determined independent of temperature and usually corresponds 35g salt per kilogram water. It can be easily determined with a refractometer. The density can be measured with the help of a hydrometer or a spindle- it should be about 1.023 at 25°C. The density of marine is however temperature-dependent and thus should be converted given the circumstances. Here you will find the matching devices for the ideal setting of salt content in the marine aquarium.