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

I've been finding that after about 3 months my pH controller starts to read my tanks pH about .2 higher than if it was freshly calibrated. For instance, in the summer the tanks normal pH range is 7.9 to 8.1 So if after a while the controller starts reading it up around 8.3 I begin the question if the controller is lying to me and if I should re-calibrate the probes. Do the rest of you experience the same thing or does your pH reading go down in time?

It's been bout 6-7 months for mine, and it's still on. When I moved the tank to redo the floor, I re-calibrated it and I was figuring it ws out. I'm not doing much other than monitoring, not using rector with it or anything

Go
 

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.
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Roll A Joint

LOL, ya I had a HUGE sponge on mine LOL

yup. try re-calibrating and see if that helps. Whenever I get a reading I am not sure is right, I will re calibrate. It's easy to do and that way you can trust your readings.

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

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

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:

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