ps233 PH results do not match Hanna digital PH tester!

[mwsmith2]

Color perception, possibly...although that is a pretty big difference in terms of color.

Michael

[waterbear]

pH meter electrodes do go bad, especially if they have not been stored correctly or allowed to dry out. That could be a possible source of the the problems. The probe could also need cleaning as per the instuction manual. I have had a lot of laboratory experience with pH meters and that would be my guess.

[Amir]

The Hanna unit was purchased 2 months ago, stored in storage solution, soaked in ph 7 for 2 hours before use (when new) and when placed in PH 7 or PH 10 calibration solution shows correct ph number. I work with color as part of my work (garphic design) and if I could not tell the correct color, I would be out of business. I understand it is the tone not the intensity of color - more orange is lower ph, more pink is higher ph. I guess I need another source to check my numbers - maybe a pool company. I check again this morning, the meter shows 7.6 and the drops show ~7.2! Any one lives in near me that can check their tap water so we can have standard? the meter shows 7.7 for the tap water. Regards

Amir

[waterbear]

Have you tried checking the pH of the pH 7 standard with the drop kit? Might prove enlightening. Phenol red indicator is pretty accurate but I have seen standard solotions that have changed pH. Depends on how they were stored and how fresh they are. I still lean toward the phenol red indicator.