Automatic Plastic Digital PH Meters, Brand Name : Ocean Star

✔ Turn on the pH meter

✔ Dissolve each buffer solution in 250 ml of distilled water

✔ Immerse the electrode into the pH 6.86 solution.(under the temperature of 25℃)

✔ Press the “CAL”(calibration) button for 5 seconds and release

- Display screen will start flashing “6.86”

- Wait it until the display screen stops flashing.

- Rinse the electrode with distilled water and make it dry with filter paper.

✔ Repeat the above steps with 4.01 pH buffer powder and 9.18 pH buffer powder.