Quote Originally Posted by georg16nik View Post
They give 2.0 - 5.0% for potassium hydroxide, so 11.8 is approximate.
Also, there is no way my water and Your water to be the same pH and mineral content.
This spring, the water in the pipes moved from 6 pH to 10 pH. I am usually distilling water but sometimes I just use filtered tap water when I don't wanna wait for a few hours for the distiller to round up..

The water's going to make no significant difference.

The pH 11.8 of Calbe RO9/APH09 is not approximate, the way older R09 is made is to balance the developer so that there is no free hydroxide, at that point there is a very slight precipitation of p-Aminophenol free base crystals which is normal for this developer. That's been the case for over 100 years and only the later Agfa Gevaert version of Rodinal now sold as Adonal etc changed this.

The difference in pH 11.8 of Calbe R09/APH09 and Rodinal/Adonal etc's pH 14 is large but is purely because the first relies on more developing agent at a lower pH with no free Hydroxide and the second on less developing agent and a sgnificantly higher pH due to an excess of Hydroxide.