A Different Way to Think About Testing Your Saltwater Tank's Salinity Using Electrical Conductivity

As reef tank owners, we have come very comfortable with our classic analog refractometers for measuring salinity but the facts are, something better does exist. Hanna Instruments took a page from their experience producing lab-grade scientific equipment and produced the HI98319 Marine Salinity Tester that works using conductivity instead of a light refraction.

Conductivity is the most common way to measure salinity in a lab environment because it is less prone to inaccurate or skewed readings. Combine that with a built in digital thermometer using graphite probes for accurate temperature compensation and you get one the most accurate digital salinity monitors commercially available to reef aquarists. The Hanna Salinity meter will provide accurate readings down to ±0.001 Specific Gravity or ±1 PPT. Unlike many other conductivity based meters, Hanna has injected the necessary conversion to provide readings using PPT, PSU or Specific Gravity units, whichever you prefer.

The accuracy is made possible because of the accurate thermometer that is built right in that reads in either °F /°C. As we know, temperature has a profound impact on salinity measurements. Most refractometers have built in ATC or "Automatic Temperature Compensation" for this very reason. The difference, however, is your Hanna device is using the real live temperature of your tank water to produce the final salinity reading as opposed to the reading of only a small sample.

Outside of reliable accuracy, there are some additional bonuses here. Formost the device is super quick and easy to use. Turn it on, dip it into your tank and get both your temperature and salinity readings within seconds. Rinse it with freshwater and store it away in the included protective case. The device is small and intended for handheld use in and around aquariums. It is waterproof which helps in the longevity department, just be sure to keep an eye on the battery indicator and replace the CR2032 Li-ion battery as needed.

It is best to reference the meter often and calibrate for accuracy at least monthly so be sure to always have a substantial supply of 35 ppt calibration solution on hand. You can quickly check accuracy by dipping the meter into a sachet of 35 ppt solution before use. If it reads correctly, proceed with your measurements. If the reading is outside the window of accuracy, proceed to calibrate.

How To Calibrate The Hanna Instruments HI98319 Marine Salinity Tester

1. Power ON the device using the ON/OFF button.
2. Press the CAL button to enter calibration mode from measurement mode. The meter will display “35.00 ppt USE” message, with the CAL" tag blinking.
3. Pour 2” of standard calibration solution into a beaker or suitable glass container.
4. Submerge probe tip to a minimum of 1.18" into the calibration solution, the meter will automatically recognize it.
5. The “REC“ message will be displayed when the calibration reading is stable and is accepted. After acceptance, the “Stor“ message is displayed and the meter returns to measurement mode.
6. **If the standard calibration solution is not recognized or is out of the accepted range the “--- Err“ message is displayed. Verify proper calibration solution and try again with a new solution if necessary.