3 in 1 Water Quality Tester PH TDS TEMP Meter Portable MultiPurpose Test Pen for Testing Water Item Type: Water Quality Tester Material: ABS Weight: Approx. 164g / 5.8oz PH Detection Range: 0.00-14.00pH PH Resolution: 0.01pH Error: ±0.05pH TDS Detection Range: 1-9990ppm TDS Resolution: 1ppm; 0.1ppt Error: ±2%F.S Temperature Detection Range: 0-60℃ Waterproof Rating: IP65 Working Environment: 0-60℃ (32-140℉); RH100% Temperature Detection Range: 0-60℃/32-140℉ Temperature Resolution: 1℃/℉ Error: ±0.5℃ Automatic Shutdown Time: 5 minutes Battery: 3 x LR44 batteries (Not Included) How e: 1. Wash the electrodes of the PH meter with pure water. 2. Immerse the pH electrode in a mixed phosphate standard buffer solution with a pH value of 6.86 (at 25°C) and stir gently. Then stand still and read. If it does not display 6.86, press and hold CAL for 5 seconds and let go, and wait for the meter to automatically recognize calibration, 6.86 is displayed, that is, the calibration is successful. 3. Clean the electrode again with pure water, and then insert the electrode into the pH4.00 potassium hydrogen phosphonium dicarboxate or pH9.18 borax standard buffer solution for calibration. The calibration method is the same as 6.86. 4. After about two minutes, the displayed value should be within the allowable error range compared with the pH value of the buffer solution. The so-called two-point calibration is to calibrate with two specifications of calibration fluid, and the three-point calibration is to calibrate with three specifications of calibration fluid. Generally start calibration from 6.86 first. Then using 4.00, 9.18.