Digital pH Tester Pen 0.01 Hi-Accuracy for Water Quality and Hydroponic Testing Features: 1. Ensures that your pool, standard hydroponics pH, or even drinking water maintains an ideal pH balance and is safe to use with the Precision pH Tester. 2. Equipped with a sensitive electrode sensor for precise pH readings. The included detailed manual will guide you on achieving the most accurate and stable results. 3. Temperature compensated for accurate readings at the standard measurement of 25 degrees. When the solution temperature varies from 25 degrees, the device automatically corrects to minimize error and enhance accuracy. 4. Perfect testing tool for both home and laboratory applications. Suitable for assessing water, swimming pools, aquariums, spas, hydroponics, food, wine, and beer brewing, among others. 5. The pH meter features an auto-calibration function that adjusts for water temperature and quality; simply wait a few seconds during testing for a pH reading. Operation Tips: 1. If inactive for 5 minutes, the meter will automatically shut down to conserve battery life. 2. Ensure the pen's tip is immersed in the solution at a depth of less than 4cm. Calibration Methods: 1. Switch on the device and verify that it is in working condition. 2. One-point calibration: immerse the device in a 6.86 solution, press and hold the "CAL" button for 5 seconds, then release. Wait for the screen flashing to complete calibration. 3. Two-point calibration: place it into a 4.01 solution, press and hold the "CAL" button for 5 seconds, then release. Press the "CAL" button again to enter 4.01 calibration mode. Wait for the flashing to finish for calibration. 4. Three-point calibration: immerse in a 9.18 solution, press and hold the "CAL" button for 5 seconds and release. Press the "CAL" button twice to enter the 9.18 calibration mode. Wait for the completion of the flashing for calibration. Indicators for Calibration Necessity: 1. The device has been used or stored for an extended period after calibration. 2. Electrodes are used frequently. 3. High accuracy is a requirement for measurements. 4. Failing to press the "calibration button" for an extended period will necessitate recalibration. Package Includes: 1* pH test pen 1* Instruction manual 1* Storage box 3* Calibration powder Note: 1. Allow for 1-3 mm error due to manual measurement. Please ensure you are aware before ordering. 2. Allow for 1-3g weight error. Please ensure you are aware before ordering. 3. Due to photo lighting and monitor differences, the images may not accurately represent the actual color of the item. Please ensure you are aware before ordering, thank you!