Before you start accusing someone of not knowing what they are talking about
you better know a liitle about them first. I have done extensive tile and
grouting. There are three basic types of grouts
Concrete based grout: Main Ingredient - Portland Cement which is predominantly made from Calcium Sulfate. Cement can affect the PH. Usually increases.
Furan Resin grout: All possible ingredients - phenol, formaldehyde, urea-formaldehyde resins, furan, furfuryl alcohol, furanic-based composite
Epoxy Grouts: Main ingredient - polyepoxide is bisphenol-A
Personally I wouldn't grout them but it isn't my system.