I've been using CRS for a couple years, but now these posts have me wondering if I should try something different.
Read and ponder but don't take some of these posts too seriously.
My water supply here in Vienna is:
125ppm alkalinity as CaCO3
2ppm chloride
7ppm sulfate
Your alkalinity (2.5 mEq/L) is going to require 2.2 mEq/L (this will vary a small amount depending on the pH of your water and the pH used to define alkalinity) and, as AMS/CRS is an equinormal mix of HCl and H2SO4 you will wind up with an extra 1.1 mEq/L each of Cl- (39 mg/L) and SO4-- (52.8 mg/L). With your low levels of chloride and sulfate CRS seems very attractive if you are comfortable with 41 mg/L chloride and 60 mg/L sulfate.
AJ has been highlighting CRS use for years, but I can now say that we are fortunate its not available in the US. A brewer is far better off using sulfuric or hydrochloric, but not both.
This is nonsense. A brewer should have in mind how much chloride he wants and how much sulfate he wants. If he has alkalinity to dispose of then use of the acids to obtain those ions is certainly attractive. The only problem with AMS/CRS is that the ratio is fixed. As the numbers above show these products impose a Cl:SO4 ratio of 0.74. But we are all too sophisticated here (I hope) to fall for the chloride sulfate ratio hype. OTOH we need to be aware of the fact that chloride also gets you sulfate with AMS/CRS and conversely and if you don't want both then you'd be better off using the acid whose cation you want. I don't like sulfate and so would never use either of these products preferring straight HCl. But clearly there is demand for the blend and clearly the ratio was chosen to scratch the itch of commercial brewers in the UK who wouldn't be buying the stuff if there were any truth in the quote.
And, for the record, I highlight it as an option for brewers to whom it is available and for whom the amounts of Cl- and SO4-- imposed by their alkalinity and the equinormal nature of the product, as, perhaps, adjusted by salt supplementaion, are acceptable.
While we can easily accept fairly high sulfate in our beers, it becomes quite minerally when paired with high chloride.
From the brewer's point of view it is convenient to think of the amount of mineral quality in water as being imposed by the anions (which must, of course, be balanced by the cations). As an example of this note that we say that a water of high mineral content is 'hard' and a low one 'soft' referring to the calcium and magnesium ion content. As you have few anions other than bicarbonate, the nature of your water is driven by the (approximately) 2.5 mEq/L sodium, calcium and magnesium in it. At the tap these are balanced by bicarbonate and you are replacing those ions with sulfate and chloride ions in a fixed ratio. If you bought HCl and H2SO4 separately you could control the ratio but would still have to replace most of the bicarbonate ions. Now if you do that all with chloride you would have a brewing water that I would like (I don't like sulfate) and if you did it all with sulfate you'd have a pretty thin, flat tasting beer and if you did it all with phosphate you would not get the body effects of chloride or the hops synergy with sulfate etc the point being that the flavor quality of mineral effect depends on the relative amounts of anions with the magnitude dependent on the total ion content half of which is cations. If the water us too minerally it is because there are too many minerals in it and the appropriate action is to remove hardness by traditional means or all minerals by RO.
Most of us understand that chloride and sulfate do not have some sort of log antagonistic effect (though adherents of the Cl:SO4 ratio theory clearly do believe this is the case.) Thus there is nothing wrong with having chloride and sulfate ions in a beer as long as the amount of each is what you want it to be. Again I cite myself and an example of someone for whom the correct amount of sulfate is usually 0.
Using your calculator, it seems as though the CRS doesn't raise the chloride or sulfate levels to excessive levels, but maybe I am missing something.
No, you aren't.
Is my water profile an exception because of its low mineral content,
Yes, you do have unusually low Cl- and SO4--. If your chloride were 100 mg/L and sulfate 200 then you might want to think about using an alkalinity combating scheme that added more of either or both.
...or should I really stop using CRS?
No, unless you want water with less overall mineral content, in which case RO or lime softening would be the way to go or you do not want any more sulfate or any more chloride than you already have in which case you could use either HCl or H2SO4 alone or lactic or phosphoric acid.