This 5-in-1 water quality tester is the ideal tool for measuring pH, temperature, conductivity, TDS (total dissolved solids), and salinity in water. It is designed to be easy to use and offers high accuracy for your aquarium, gardening, or other applications requiring water quality control. Technical Specifications Automatic Calibration Backlit LCD Display IP67 Waterproof Auto Shut-Off Easy to Use Compatibility and Accessories 5-in-1 Water Quality Tester pH 4.00 Calibration Powder pH 6.86 Calibration Powder pH 9.00 Calibration Powder Operating Instructions Installation Before starting use, it is recommended to calibrate the pH meter with the provided calibration solutions. Add the buffer powder to 250 ml of distilled water and stir until completely dissolved. Usage To use the pH meter: Press the "ON" button to turn it on. Immerse the electrode in the solution to be tested and wait for the measurement to stabilize. After each measurement, rinse the probe with distilled water and dry it