I have spent some time reading and attempting to understand water adjustments for brewing, but I am only getting more confused.
With so many variables in this process, I understand why most of the posts on this subject do not result in any clear agreement.
Let alone lots of people do not like using 5.2 mash stabilizer, but I have seen that BierMuncher uses it and likes it and we are using similar water to brew with.
I am St Peters MO - using basically the same water that AB uses in St Louis MO.
The water is river based and has a high PH and is moderately hard as I understand it.
The local micro brewery does nothing to the water for any of their beers, not even filter. Basically everyone I have asked in the area says the water is great for brewing. I have found the local water analysis and it does seem to be good for brewing based on using the ez calculators, etc.
But I like to over complicate things
I charcoal filter, use a Camden tablet and add 5.2 stabilizer to the water before I BIAB mash.
My water is around 9 ph out of the tap and after adding 5.2 mash stabilizer to the water I must be around 5.2 as advertised, see the before and after pics, using my pool ph measuring system. ( I did not add the chlorine stuff in the after pic )
I just learned to check my PH of the mash during the mash... I wish I knew that yesterday when I was brewing...
So next time I brew....
If my beers continue to taste good and if I check my ph during the mash next time and it is close to 5.2 while mashing... I guess I am good.
I have used both lactic acid and phosphoric acid.
Both work. Not sure I can tell the difference with my beers.
With either acid I use only about 2ml for about 10lbs of grain.
Not much is needed with my soft water.
There is lots of good advice on this site, but it does take some digging
to figure out how to apply it to a particular situation. At least it did for me.
I am not a fan of the 5.2 stabilizer. Seems like it adds a lot of sodium.
If you are going to worry about ph level, then a ph meter is necessary.
No way around it.
The ph level of the water can be/should be ignored.
All you really want to know is the ph of the mash.
It is difficult to calculate how much acid to add to a mash to
change the ph a desired amount. Much easier to dilute your acid
1:100 with water and add incremental amounts until you hit your target ph.
The first time it is a bit of a work, but easier on successive batches
because you have a better idea of how much acid is needed.
But you need a ph meter.
Add the acid to the mash, not to the mash water.
If you have folks in your area using local water untreated and producing
beers you like to drink, maybe skip the ph meter and ph adjustments entirely.
Charcoal filter and campden tablets will not change the ph (I think).
5.2 ph level is not ideal for all beers.
And the ph range that will work is large.
Maybe try a batch with RO water instead of local water and see if you
can tell the difference in how your beer tastes.
Lots of random thoughts above. Everyone has their own opinion on this stuff.
Easy to get sucked into a lot of little details that may not make a difference.
In general no good rules of thumb.
There are some water calculators out there that might get you close.
But you will need a current water analysis, and they may not work well if you use 5.2 stabilizer.
I am skeptical of the water calculators (as far as ph level) because I find that just changing
my base grain from one vendor's pale malt to another vendor's changes my mash ph.
Not an issue at all if you have a ph meter. Just a little more or less acid.
I have seen some rules of thumb for using acidulated malt on these forums.
But it may not be compatible with the style of beer you want to make. And you probably need to
start with RO water instead of tap.
I have heard of commercial brewers treating their water instead of treating the mash.
But they probably know exactly what kind of water, what kind of grain, and a full lab to back them up.