Salinity Measuring

In freshwater aquariums, salinity typically isn’t a concern, as tap water usually has a negligible amount of salt that won’t affect the ecosystem. However, in saltwater aquariums, maintaining the correct salinity is crucial. The majority of marine species thrive in a specific gravity (SG) range of 1.019-1.025.

Why Salinity Matters

Salt does not evaporate, which is why you should top off your tank with freshwater rather than saltwater. As the water evaporates, the salt remains, so once you’ve achieved the desired salinity, you just need to keep up with regular top-offs. The salinity will stay stable as long as you avoid adding more salt during these top-offs.

Tools for Measuring Salinity

To accurately measure salinity, you’ll need the right tool. There are two common options:

• Hydrometers: These are the more affordable choice but tend to be less accurate. They work by comparing the weight of saltwater to pure water, measuring the specific gravity.

• Refractometers: These are more accurate and use the principle of light refraction. The dissolved salt bends light differently than pure water, allowing refractometers to measure salinity directly rather than total dissolved solids like hydrometers do.