pH rapidly rising

[Imogenlucie]

Hi there everyone. I have just purchased a new betta and I'm still very new to fish keeping. I previously spent around 6 weeks cycling my 5 gallon tank prior to introducing my betta fish. He’s on day four now and seems to be thriving, but the one thing I’ve noticed is that my pH steadily climbs daily. Ammonia and nitrites reading as zero and nitrates steady at <20ppm. Water when added to the tank is at pH7. I performed a 30% water change yesterday when pH started rising. pH was reading at 7 at the time of the water change. 24 hours later my pH is reading at around 7.8-8ish. I'm measuring all levels using the API freshwater test kit. I add Seachem Prime at every water change. Temperature in the tank is steady at 24 degrees C and I have a low flow filter. Any advice as to what could be causing my changes in pH is welcome! I have three live plants, an ornament and a decorative rock in the tank as well as a single mystery snail. The rock is made from granite. My substrate is gravel. Thanks so much in advance.

[Aiken Drum]

Tapwater pH can increase as CO2 degasses. Try leaving some tapwater out overnight and testing it. That will be the actual pH of your tapwater.

If your fish is healthy the pH isnt an issue. They can acclimate to a wide range of pH.