Well, before I post this I want you guys to know that I thought about this for at least a little while. I'm NOT the type of person who wants to pick a fight, especially about one of my favorite subjects in the world, brewing. Let me start by saying I believe there are many roads to good beer and if you divide these roads into the subsection that is brewing water you still have a few roads to choose from. For ME, this total alkalinity is just fine, I can deal with this and brew Beirmunchers Centennial blonde. Let me take one step back. I believe that the lightest color beer, the beer with the lowest SRM grain bill, aside from a lager, let's stay on ale here, can serve as a benchmark for the grain bill that probably isn't going to help the mash pH go down. Roasted malts and darker crystals malts will aid the pH drop, I don't think there is any argument that your Stout will be easier to convert (from starch to sugar in the Mash) than a 3.9 SRM Blonde Ale. So in this example with YOUR water, for a 5.5 gallon batch using the grain bill here in the recipe section under Beirmucher's Centennial Blonde Ale (if you haven't made this you are missing something special) 7# 2 row US, .75 Cara/dex, .5 10L, .5 Vienna = 8.75# grain. My pre-boil volume is 7.6 and I'm going to mash at around 1.2 ratio so my mash water is about 2.5 gallons. Now, just a little about 'my road' to beer water. I 'believe' in Cl/SO4 ratio's... I 'believe' in Residual Alkalinity... That said I try to use as little as possible and target a room pH Mash of 5.5... My water, deep well, has a bicarb of 166, yours is about 30 points higher but I would use what I use, Lactic Acid to treat just the mash water. Again, I 'believe' that after I turn the conversion off (between 168 and 172ish depending upon the type of Mashin' yer doin') the water chemistry doesn't matter AS MUCH, chloromines still matter and they should be removed from all water. Specifically for YOUR water, I'll use my 10 gal brewpot cause I don't know whatcha got over there, I would do the following, just make the additions to the mash water...1.5 ml of Lactic Acid, 1.5g gypsum, and .5g of CaCl, this gives you an estimated dead center room temp Mash pH (you want it between 5.4 and 5.6), heat this water up to strike temp ~ 163ish and Mash for 60 min at 150 for the finest Blonde Ale this side of the Pacific ocean.
Again, disclaimer, this is just the way I brew, I try to make it as simple as possible, a little salt and a little lactic acid...
Starting Water (ppm):
Ca: 55
Mg: 27
Na: 17
Cl: 25
SO4: 4
HCO3: 191
Mash / Sparge Vol (gal): 2.5 / 6.24 RO or distilled %: 0% / 0%
Total Grain (lb): 8.8
Adjustments (grams) Mash / Boil Kettle: CaSO4: 1.5 / 0 CaCl2: 0.5 / 0 MgSO4: 0 / 0 NaHCO3: 0 / 0 CaCO3: 0 / 0 Lactic Acid (ml): 1.5
Sauermalz (oz): 0
Mash Water / Total water (ppm):
Ca: 105 / 69 Mg: 27 / 27 Na: 17 / 17 Cl: 50 / 32 SO4: 92 / 29 Cl to SO4 Ratio: 0.55 / 1.10
Alkalinity (CaCO3): -29
RA: -121
Estimated pH: 5.50
(room temp)