How to use a water tester digital Ph meter,calibration PH meter

Описание: Portable High Precision Water Tester Aquarium Digital Mini Ph Acidity Meter Pen type.www.cnhealthshining.com,what'sapp:richard 0086-18658896852
How to Calibration the pH meter?
1. Turn on pH meter
2. Disolve each buffer solution in 250 ml of distilled water. (at 25℃/77℉ temperature)
3. Immerse the electrode into the pH 6.86 solution.
4. Press the "CAL" (calibration) button for 3 seconds and release
-Display will start flashing 6.86
-Wait until the display stops flashing.
Rinse the electrode with distilled water and dry it with filter paper.
5. Immerse the electrode in pH 4.00 solution,
- Press "CAL" button for 3 seconds, then press and release immediately second time
- Reading will start flashing 4.00
- Wait until display stops flashing
Rinse and dry the electrode with distilled water as before.
6. Test calibration by inserting electrode into pH 9.18 buffer solution, gently swirl electrode until digital display stabilizes. Display should read between 9.16 and 9.20.
(if necessary repeat calibration procedure)