And right there is where you have introduced the confusion. Hardness is due to the presence of calcium and magnesium ions in the water NOT carbonate species, It is NOTHING to do with carbonate/bicarbonate ions. YES hardness is most likely to be associated with carbonate/bicarbonate ions, and referred to, badly, as temporary hardnessCarnot wrote: ↑Mon Feb 12, 2018 7:27 amI can understand the confusion that some people are having with hardness determinations and alkalinity. The term hardness came about from soap manufacturers and the use of steam in industry. Hardness is normally defined in terms of temporary and permanent hardness, which is usually assumed to be due to calcium and magnesium salts. In simple terms most hardness in potable water is due to carbonates, usually existing as bicarbonate.
Personally I think it's important to make a distinction between hardness (calcium and magnesium ion levels) which is good for brewing, and alkalinity (carbonate species and hydroxide ions), which is not really required in brewing at all. When yo start bringing imprecise terms from other industries into the mix confusion will occur.