Just to point out there is no simple relationship between pH and alkalinity.Kingfisher4 wrote: ↑Thu Dec 06, 2018 2:28 pmInterestingly, many of the bottled water varieties seem to have quite a high pH. Tesco Ashbeck water is the lowest I have found, Only became aware of this because of the potential problems with diluted starsan which quite rapidly goes milky and becomes apparently less effective in high pH water, e.g. our tapwater.
A small quantity of acid added to pure water would cause its pH to fall rapidly and be less than pH 7.
The same amount of acid into alkaline water, such as mine, would cause a vastly slower rate of fall in pH. Even after pH fell to 7.0 the rate of fall per unit of acid would be vastly less than observed in liquor without alkalinity. Only after a significant greater addition of acid and when pH was tending towards pH 4.5, the accepted end point for alkalinity, would the rate of change in pH approach that observed in pure water.
Mashing beer is slightly more complicated, but in the case of dilution of beer the circumstances are exactly the above in reverse. Add some distilled or deionised water and there will be little problem that while pH will rise by dilution it will be small in terms of pH as it is measured on a logarithmic scale. Adding alkaline water will be very different as not only will pH be diluted, but acid in the beer will be neutralised by the alkalinity. Now its pH will rise more quickly due to the depletion of the acid and the naturally low pH that gives both protection from bacterial infection and enhancement of the many flavours we desire may be detrimental in some circumstances.