Seawater specific gravity (SSG) is an indirect measure of seawater density. Saltwater is more dense than pure water because it has a higher content of dissolved salts and minerals.
Different species of aquatic life thrive in freshwater and saltwater, with most species being very sensitive – so even very small changes in the saltwater density can affect the organisms within the aquatic ecosystem.
Specific gravity of sea water testing is useful for various applications, including aquaculture, desalination plants and oceanographic research.
Aquaread’s SSG parameter is a calculated using the conductivity and temperature measurements.
The output for the TDS measurement is SigmaT or ST, a unit used in oceanography for measuring water density at a given temperature.
Our SSG sensors come as standard on many of our probes, below are some examples.
To see all of the probes that feature SSG please visit the Products section.
The SSG parameter is included on every Aquaprobe and Aquasonde, it is also included in the AquaPlus optical dissolved oxygen sensor.
An SSG sensor can be used in the field to take direct measurements of water. The probe that is inserted into the water sample applies a voltage between electrodes of the EC sensor. The drop in voltage measures the resistance of water, which is converted to conductivity.
From this conductivity measurement the SSG is calculated incorporating the temperature reading in the calculation.
SSG is closely linked to the EC of the water, the EC of water has a critical influence on aquatic life. Every kind of organism has a typical range that it can tolerate. In a commercial sense, testing the conductivity of water may be specifically useful for fisheries. Salts and other substances also affect the quality of water for irrigation or drinking, so water conductivity and water density meters can be used when testing the output of water treatment plants.
The water conductivity meter is just one function of Aquaread’s multiparameter water quality monitoring equipment. Use all the parameter readings together to accurately monitor water quality without the need for multiple probes. The EC water testing equipment is suitable for use on surface water, groundwater and wastewater.