PH Meter Digital 0.01 High Precision Water Quality Tester with 0-14 Measurement Range for Aquarium Swimming Pool Ideal for household or laboratory use, suitable for testing pH balance of drinking water, pool, aquarium, food projects, RO system, spa, or hydroponics. Specifications: Measuring range: 0.00–14.00 pH Resolution: 0.01 pH Accuracy: ±0.01 pH Batteries: 2 x 1.5V LR44 (not included) Automatic temperature compensation: 0–50°C (32–122°F) Dimensions: 15 x 2.5 x 1.3 cm / 6 x 1.1 x 0.5 inch Net weight: 52g / 1.83 oz Usage Steps: Step 1: Turn on the pH meter and clean the electrode with distilled water. Step 2: Immerse the electrode in pH 6.86 standard buffer solution. Step 3: Press the "CAL" button. Wait until the display stabilizes at 6.86 pH. Step 4: Clean the electrode with distilled water, dry gently, then immerse in pH 4.00 standard buffer solution. Step 5: Press the "CAL" button. Wait until the display stabilizes at 4.00 pH to complete calibration. Step 6: Clean and dry the electrode, then place it in pH 9.18 standard buffer solution. Verify reading is within 9.17–9.19 pH. Instructions for pH Calibration Powder: pH calibration powder is a solid standard substance. Dissolve in water to prepare standard solution. Suitable for calibrating any type of pH meter. Each packet prepares 250 mL of solution. Note: Add water in the correct ratio to ensure accuracy and minimize calibration error. Precautions: The pH pen probe contains glass components and is fragile. Avoid impact or collision. Do not attempt to replace the probe if damaged. After use, gently blot the probe dry with absorbent paper. Note: The pH meter is factory calibrated. Recalibration is only necessary in the following cases: - After prolonged use following calibration - Frequent electrode usage - When high measurement accuracy is required