Sea water specific gravity (SSG) sensor

What is Electrical Sea water specific gravity (SSG)?

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 Sea water specific gravity (SSG) Sensor.

Aquaread’s SSG parameter is a calculated using the conductivity and temperature measurements.

The output for the SSG measurement is SigmaT ST, a unit used in oceanography for measuring water density at a given temperature calculated using salinity and temperature measurements.


Key Features

  • Calculated parameter that’s always included on every Aquaprobe and Aquasonde.
  • Uses the Corrosion resistant gold coated stainless-steel EC sensor.
  • Measurement range 0 – 50 ST.
  • Resolution of 0.1ST.
  • Accuracy of 0.1ST.
  • Requires no calibration – this is taken care of when you calibrate the EC sensor.

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.



Portable, GPS AquaPlus Optical DO/EC system



Advanced portable multi-parameter Aquaprobe.


LeveLine CTD

Adds conductivity and salinity measurements

Always included

The SSG parameter is included on every Aquaprobe and Aquasonde, it is also included in the AquaPlus optical dissolved oxygen sensor.