Actually, this started when I wanted to make my own alkaline water with a PH of about 9.5, not 12.5. When I set up a sample problem, my (erroneous) calculations showed I should get a pH of around 12. I was surprised to get only about 8. Now I know the reason. There are some recipes on the Internet about how to make your own alkaline water using baking soda. I will have to check them out to see if they really work.