Our new HI-98319 waterproof salinity and temperature tester is perfect for any saltwater aquarium. A more accurate alternative to refractometers, this tester uses conductivity to determine salinity levels of natural and artificial seawater. Ideal for testing salinity in salt water aquariums, it is quick and easy to use and provides digital readout of both salinity and temperature. Salinity results are displayed in either parts per thousand (ppt), Practical Salinity Units (PSU), or Specific Gravity (SG).Our marine salinity tester is supplied complete with batteries and solutions allowing you to start measuring right away. Also displays temperature.