Calibration and technical troubleshooting

 
Regardless of calibration or switching on and off the screen shows a fixed number; This means the pH meter froze (this does not happen often but sometimes still). Just take out the batteries from the black lid top on top of the pH meter, wait a few seconds and insert them back in. Problem solved.
Usually the meter works well but calibration can be tricky if using and calibrating a pH meter for the first time. After holding the meter in 6.86 solution and pressing the "Cal" button for several seconds, 6.86 should start blinking. Rinse the meter with distilled water and put it into the 4.0 solution. Here is the tricky part. Hold down the "Cal" button for 4-5 seconds. Once you release it, 6.86 will blink again. Immediately press "Cal" button for a second, release and the meter will show 4.00. Once it finishes blinking, your meter is calibrated. If you don't get the 4.00 reading. It did not calibrate. Start again from 6.86 and make sure you don't get 4.0 in the 6.86 solution or the results will be off. What happens is sometimes we forget to hold the "Cal" button down for 4-5 seconds or push the button for a second time after 6.86 starts blinking.
This usually happens if there is a mistake in calibration. Sometimes we forget to push the "Cal" button again for it to calibrate for the 4.0 solution and instead it calibrates in the 4.0 solution for a measurements of 6.86 (2.86 points higher). If you then measure your water of 7 - it would show around 9.8. This also happens if you switch the meter on and off between the calibration solutions and the meter thinks that the 4.00 solution is the 6.86.
This can be a tricky and frustrating one as you may have calibrated several times without any luck. One of 2 things is at work here: 1.) The probe has been damaged during transportation or is defective 2.) More than likely there are air bubbles inside the pH probe which result in unstable results. Air bubbles inside the pH glass membrane are normal and cannot be removed. They will not cause problems if they are at the upper end of the probe. Read the next question to see the fix.
Air bubbles inside the pH glass membrane are normal and cannot be removed. They will not cause problems if they are at the upper end of the probe. Air bubbles can get trapped in the electrolyte solution of the reference system. This results in unreliable and unstable readings and may make it impossible to achieve a reading. In order to remove air bubbles, shake the probe vigorously using a downward motion so that the air bubbles move to the upper end of the probe. If air bubbles are trapped inside the solid KCl crystals, heat the electrode tip in warm water (max. 60°C). This will dissolve the crystals and release the air. Afterwards, shake the probe down once more as described above and leave it to cool down.

Interested how to keep your pH meter working for years not weeks? Check out our maintenance guide

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