In recent weeks this has become an area of interest for me, mainly because it's a very challenging subject, and I like challenges. So I've done a bit of reading.
Since my OP, my water supplier has changed location of their treatment works and my water is now 180ppm, not 427ppm. Improvements are seen all over my home, the shower head, the iron, the kettle, sink/shower cleanliness, I could go on. I've brewed one kit with the new water, it's still in the fermenter, initial sample suggested a softer profile. I'm hoping for (expecting) less salty beers which hold their head longer.
I now also hold a report offering all the mineral levels in the new supply, so I start to dig into Palmer's spreadsheet to understand the affect of additions. So my general understanding of the subject has improved a lot, but I am still plagued with what are probably basic misunderstandings. In Palmer's spreadsheet, you can represent Alkalinity as either CaCO3, or as Bicarbonates in ppm. I'm still a bit confused as to the difference between these two, and in particular, what am I looking at in my water report? To be clear, I live in Alsace and my water report offers my "hardness" as 18 French Degrees. I see that this equates to 180ppm, but is that 180ppm CaCO3, or 180ppm of bicarbonates? My guess is the first; please tell me if I'm wrong.
So if I know my water is 180ppm CaCO3, then why would I need to test Alkalinity? Doesn't this report give me this figure? If the test is simply about confirmation of what actually comes through my tap, then I get it, but if the 180ppm CaCO3 is not Alkalinity at all, then I remain confused. Thanks for untangling me.