1. Water quality testing This digital LCD water quality tester measures the quality and purity of tap water over a range of 0-9990 ppm. It is suitable for use with water purifiers, filters, pools, spas, aquariums, hydroponics, and can help monitor the purity of foods and beverages. 2. Practical features Includes a Hold function to store measurements for easy reading and recording. Auto-off after 10 minutes of inactivity to conserve battery life. Dual-range measurement: 0-999 ppm (1 ppm resolution) and 1,000-9,900 ppm (10 ppm resolution). 3. Precise and reliable Accuracy is ±2%, providing consistent results so you can assess the purity of your water sources with confidence. 4. Easy calibration Calibration is straightforward: hold the temperature button to enter calibration mode, adjust with the +/- buttons, then press the temperature button again to finish. The display shows calibration status with blinking text during the process. 5. Practical applications - Verify drinking water quality and the output of home purifiers or filters - Monitor water in aquariums or hydroponics to protect fish and plant health - Check pool or spa water to ensure sanitizer and overall quality levels are appropriate