On Sat, 13 Jun 1998, I mistakenly wrote > Noncarbonate hardness is > the amount of the general hardness that is not balanced by carbonates in > solution. It's calculated as alkalinity minus general hardness, or 0, > whichever is largest. Actually, general hardness minus alkalinity, or 0, whichever is largest. Wouldn't it be clever of me to proof my letters *before* I sent them? Roger Miller.