A couple things that stood out to me in the new Modern Homebrew Recipes book I picked up today…
What are the effects of 10% phosphoric acid in RO water?
Secondly, normally I’ll add CaCl2 into the strike and sparge water to dissolve. Gordon Strong mentions to add the X amount of CaCl2 “to the mash”. Is he referring to just dumping the dry salts into the mash and stirring them up at that point?
It lowers the pH with minimal additions since RO water has little buffer capacity. Most of the popular water adjustment spreadsheets can help you predict the magnitude of the change. You aren’t likely to need to use acid to lower the pH very often if you are brewing with RO or distilled water.
My assumption would be that he means add all of it to the mash as opposed to reserving some for the sparge water.
I believe all the additions should be made to the mash. G. Strong advocates adding the crystal and roasted malts at the end of the mash plus he sparges with RO water so there is no need to adjust the sparge water.