I read an article recently and it talked about the water used for making hoppy pale beers and had some tips and suggestions from a very good hoppy beer home brewer. He said he starts from scratch, using RO water and adds Calcium Sulfate and Calcium Chloride to get around 250ppm Sulfates and about 100-125ppm Calcium, with a Sulfate:Chloride ratio of 5:1.
That's a lot of sulfate but some people like that. I usually recommend starting at a lower level and working one's way up because a lot of people don't like that level of sulfate. Fifty ppm chloride is a pretty good starting level but you should experiment with that too. The notion that the ratio of chloride to sulfate is important is probably one that were best forgotten. It is the absolute amounts of the ions that count - not their ratio.
I understand brewing salts and how to use them to get these numbers. But what I am confused about is the other ions. If you started out with a completely blank slate from RO water this would give you; Ca: 125 Mg: 0 Na: 0 S04: 250 Cl: 50 Total Alkalinity: 0 RA: -89.
If you want the qualities that other ions give you (sodium tang, magnesium sour bitterness) you can employ salts that give you those ions. In most beers you don't need them. RA is useful for comparing water supplies and giving one a rough idea of what adjustments he might need to make in order to use a particular water for a particular type of beer but in synthesis of water for a particular brew one generally isn't concerned about it. What one is concerned about is getting proper mash pH.
So although the article didn't mention so, would one also add some sort of alkalinity in this case to get the RA higher?
In a pale beer the mash pH is likely to come in high in which case you would add negative akalinity (acid). This would lower the RA. If, OTOH, you had a lot of very acidic crystal/caramel malt (tends to be the darker ones) and a base malt which is pretty acidic (Maris Otter) and a salting level that resulted in lots of calcium then you would add some alkalinity (base) which would increase the RA.
If acid is required sauermalz, lactic acid or phosphoric acid are the usual choices in the US. Those in the UK have the option of using a blend of sulfuric and hydrochloric acids which is sold for brewing mash pH adjustment.
If base is needed probably the best bet as things appear at the moment is baking soda (which adds some sodium). Pickling lime (slaked lime, Ca(OH)2 has been popular but people are starting to see things that we can't explain with it at the current time. Chalk (calcium carbonate) used to be the mineral of choice but it shouldn't be used.
Or, if you are building your water and want to hit these numbers is it acceptable for all the other ions to be 0, or would you want to add anything else to the water?
The only number you need to hit is the mash pH (5.4 - 5.6) but you do, of course, want to keep track of the sulfate, chloride and sodium as they affect flavor. It is important to note that calcium reacts with phosphates in the malt to release acid and has a secondary effect on mash pH. 125 mg/L calcium is a lot. In a nominal pale ale mash it could be responsible for lowering pH by almost 0.15 units.
