Why is my PH rising?

[Myka]

How old is the probe and what brand? Often times when probes start dying they start losing their calibration.

Fwiw, CO2 isn't the only cause on low pH. Decaying organic matter will lower the pH as well which is why many tanks that have high nitrate also have low pH.

Originally Posted by The Grizz

According to my Ph probe my tank is sitting @ 9.09.

I doubt that is accurate. Have you calibrated lately?