Well on my next brew I shall probably find out - I am now mashing in at about 55ºC so that I can do what Braukaiser calls the 'no rush pH adjustment': making any necessary adjustments to pH before reaching the enzyme activity zone.
That would be brilliant thanks
If the tool wants the parameters for my tap water, the Affinity Water report says Ca 126, Na 19, Mg ??, chloride 31-44, nitrate 22-27, sulphate 18-31 and alkalinity (as HCO3) 333. I've just sent off a sample of my water to the redoubtable Neil at Phoenix Analytic so hopefully I will soon have some rather more concrete numbers...