5 in 1 Function This is a water test kit with PH tester, TDS meter and EC salinity temperature test function. The backlit LCD screen 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 precision PH resolution is 0.01 pH, accuracy 0.05 pH. 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 use Ideal 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. If you have any questions, please feel free to contact us, we will be happy to solve your problems Please try to avoid using this pH meter to measure concentrated acid solution or alkali. Otherwise, its accuracy and lifespan will be affected.Once 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 testing. 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 to 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 The electrode is exposed to air, the display of values is slow and unstable, due to the dry electrode. You need to immerse the electrode in water for a few hours and recalibrate the device before use. 5 in 1 Water Quality Tester PH4.00 Calibration powderPH6.86 Calibration powderPH9.00 Calibration powderInstructions for use Auto calibration Backlit LCD display IP67 Waterproof Auto power off Easy to use Press the "ON" button to turn on, press the "HOLD/TEMP" button to lock the value, and press and hold "HOLD/TEMP" to change the temperature unit. Press ON button to turn on, touch MODE/CAL to switch to other modes. 1. Before calibration, add pH4.00/pH6.86/pH9.18 buffer powder to a container containing 250ml distilled water and stir until the powder is completely dissolved. 2. Press the "ON/OFF" key to turn on the pH meter and enter pH mode 3. Put the electrode into the pH6.86 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 pH6.86 reading does not flashes no longer and the pH6.86 calibration is complete. 5. Repeat the steps above to complete the pH4.00/pH9.18 calibration in order. NOTE: Always carefully follow the calibration sequence of pH6.86, pH4.00, pH9.18. Otherwise, the calibration result will be inaccurate. Fast and accurate calibration of pH meters