I have a situation where I am looking at using phosphoric acid to reduce the alkalinity of some pretty hard and alkaline brewing liquor (256 total alkalinity and 410 total hardness, both as CaCO3). A quick run of Mr. Brungard's Bru'n Water spreadsheet gives me the quantities I need to go from ph 7.2 to 5.7 for both strike and sparge water.
And then I make the mistake of turning to Appendix B of Water, where I learn about the high likelihood of precipitating hydroxyl apatite and reducing the Ca in solution to something like 35-ish ppm.
The appendix notes that this would result in a further pH reduction, which I don't see as an immediate issue -- this is for a very pale beer -- unless that pH reduction is really significant.
Are there any other significant consequences to precipitating apatite (in the HLT, pre-mash and pre-sparge)? Could it reduce the effectiveness of a gypsum addition to the mash or boil? Any other potential downstream negative consequences? Or can additional calcium additions to the mash make up for losses as apatite?
Thanks in advance!