5 in 1 FunctionThis is a water test kit with PH tester, TDS meter and EC salinity temperature test function. The backlit LCD display makes it easy to read the displayed values Easy to usePress the power button to turn on. Press "HOLD" to lock the value, long press "HOLD" to change the temperature unit. Press "MODE" to switch between different functions. Absolute Accuracy PH resolution is 0.01pH, accuracy 0.05pH. TDS meter resolution 1ppm 0.1ppt, accuracy 2%. Conductivity resolution 1uS/cm 0.1mS/CM, accuracy 2%. Thermometer resolution 0.1/, accuracy 0.5. Salinity Resolution 0.01%, Accuracy 0.01-5.00%(0.1%) 5.10-25.00%(1%) Wide UseIdeal for home or laboratory use. Suitable for testing the pH balance of drinking water, swimming pool, aquarium, RO system, spa or hydroponics Sturdy and durableThis pool tester is IP67 waterproof, so it can continue to be used even if it falls into the aquarium. Please try to avoid using this pH meter to measure concentrated solution of acid or of alkali. Otherwise, its accuracy and service life will be affected. After the pH meter is turned on, the probe will detect the pH value of the air or residual solution on the surface of the bulb sensitive, so the pH reading will appear erratic, which is normal. It is normal for readings to fluctuate up and down during the test. Never take a reading immediately after placing the probe in the solution. To read a pH meter, always wait for the reading to stabilize. After each measurement, rinse the probe with distilled water or pure water for 5-10 seconds and dry it before measuring the next solution. Otherwise, the results will be inaccurate. Sensitive bulbs are made of very fragile glass. Do not touch with hands or other hard objects, and do not use this pH meter to test solutions above 50 degrees Celsius. If the electrode is placed for a long time and the electrode is exposed to air, the display of values is slow and unstable, due to the dry electrode. You must immerse the electrode in water for a few hours and recalibrate the device before use. Auto Calibration Backlit LCD Display IP67 Waterproof< /p> Auto shut-off Easy to use Lock value/temperature switch Press the "ON" button to turn on, press press the "HOLD/TEMP" button to lock the value, and press and hold "HOLD/TEMP" to change the temperature unit. Using the mode switch Press the "ON" button to turn on, touch "MODE/CAL" to switch to other modes. Fast and accurate calibration of pH meters 1. Before calibration, add pH4.00/pH6.86/pH9.18 buffer powder to a container with 250ml of distilled water and stir until the powder is completely dissolved. 2. Press the "ON/OFF" button to turn on the pH meter and switch to pH mode 3. Put the electrode in the pH4.00 standard solution and wait for the reading to stabilize (usually 5-10 seconds) 4. Press and hold the MODE/CAL key for 6 seconds and release it until the pH4.00 reading is no longer flashing and the pH4.00 calibration is complete. 5. Repeat the above steps to complete the pH6.86/pH9.18 calibration in order. NOTE: Always strictly follow the pH4 calibration sequence, 00, pH6.86, pH9.18. Otherwise, the calibration result will be inaccurate.