Apex ph reading seems off

[Aquavaj]

My tank is reading very high ph, 8.4-8.7 throughout the day. I have cleaned the probe in vinegar but no difference. If I test with the test solutions they both read low. However I dont know how old these solutions are so they could be bad. I tested with an API test kit and it looks to be 8.2-8.4 but I always have trouble reading the colors on these color matching test kits. However I can see clearly it's nowhere near the readings on the apex.

 

[MnFish1]

My tank is reading very high ph, 8.4-8.7 throughout the day. I have cleaned the probe in vinegar but no difference. If I test with the test solutions they both read low. However I dont know how old these solutions are so they could be bad. I tested with an API test kit and it looks to be 8.2-8.4 but I always have trouble reading the colors on these color matching test kits. However I can see clearly it's nowhere near the readings on the apex.

Have you used the calibration fluid - and recalibrated it? The calibration solutions in the 'packets' are one time only - you cant save them up and re-use them (AFAIK)

 

[Mjl714]

When did you last calibrate the ph probe?

 

[drspiroraft]

You need to recalibrate with new calibration fluid.