Btw- at 104 ppm of bicarbonate, that is where a lot of your kH is from. mostly the KH in tanks comes from carbonates and bicarbonates. I am surprised you pH is 7.2 . With your reported KH I would have e expected higher. Are you reporting the tap pH or the tank pH?
I have well water and it comes out of the ground loaded with CO2 which makes the pH drop. From the tap my pH reads below 6.5. When I outgas the tap water, the pH is ranges from 7.0 and 7.4. The range is over two decades and the changes occurred pretty slowly (over years).
You can get a better understanding of this by having a read here:
https://fins.actwin.com/mirror/begin.html
Read the two sections in
Practical Fresh Water Chemistry.