Does your pH controller read too high or too low when it needs to be calibrated?

[whatcaneyedo]

there can also be some reasoning behind the .2 drop as well. in the winter you are more likely to keep windows and door's shut which will raise the indoor c02 level's. Which could potenially lower your ph

In the summer with the windows open and the CO2 levels in the house signifcantly lower the normal range for the pH of my tank is 7.9-8.1. In the winter its 7.7-7.9 and I'm doing many things to try to bring it up but that isnt what I'm asking about here.

I'm just wondering if its normal for a pH controller to start incorrectly reading pH higher when it becomes time to re-calibrate or if some people also experiance their pH reading to lower. These are the sort of answer I was looking for:

it could be either. Also, make sure to rinse the probe in ro/di water every once in a while to ensure that nothing is obstructing the sensor.

Yup, I find the error is usually higher when it needs re-calibrating.

I'm just asking out of curiosity. So far my controller always seems to slowly creep upwards between calibrations.