ChatterBank1 min ago
Why does deionised water give a different reading on my pH meter compared to pH paper?
Measuring deionised water on my pH meter I get a reading of pH8, using pH paper the result is pH6. I checked the pH meter using buffers of pH4, 7 and 10 and the results matched with the pH paper. I tried using a different pH meter to measure the deionised water and I still got the same outcome. Why??
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I supect that pH paper works fairly well in a solution that is buffered but since deionised water has virtually no buffering capacity the pH paper itself may be affecting the pH. Have you tried distilled water? It is preferable not to wipe the pH probe, rinse and shake dry in 3 changes of deionised water should be perfectly OK.