How to Test Salt Water for Electrical Conductivity

Measuring the electrical conductivity of salt water in an aquarium will help you calibrate its salinity.

Salt water conducts electricity. The salt crystals in the water carry the electrical charge. One of the most common ways of testing how much salt is in a sample of water, or the "salinity" of the water, is by using a salinometer, which is a tool that sends electrical current into a water sample and tests its strength. The stronger the electrical current, the more salt is present in the water. This test is often conducted to determine if water is drinkable or if it is suitable for a saltwater aquarium.

Things You'll Need

• Salinometer

Instructions

1. Calibrate the salinometer by rinsing the test probe in alcohol for 10 minutes, then rinsing in running water. Turn the salinometer on and dip it into a sample of purified water. Most salinometers will have a "calibrate" button or function that can then be pressed to re-set the meter's "zero" reading.

2. Insert the instrument into the salt water sample.

3. Press the "power" or "activate" button to achieve a reading. Salinity is normally measured in microSiemens per centimeter (microS/cm). A reading of 54,000 microS/cm is typical for sea water. Safe drinking water is typically 100 to 500 microS/cm.

Tips & Warnings

• Salinometers are sometimes called conductivity meters.

References

• Apps Labs: Salinity -- What Do Those Figures Mean?
• Salinometry.com: Salinometers
• Instrumart: Operating Instructions EcoTestr Salt Waterproof Pocket Tester