pH reading more that 10.5?

[almost]

Hi,

Is it possible that pH could read values more than 10.5?

I want to have a probe in kalkwasser reactor so as to know when I should add kalkpowder. The manufacture of the reactor shaid that I should add kalkpowder when pH drops from 12.4 to 12.0

[Coralleida]

It's interesting......