Why Can't I find a water Calc that gives me accurate pH?

So I have tried nearly all (if not all) water calcs out there and while they all jive with mineral contents none of them jive with ph. Not only are they off... they are usually way off. I have been using bru'n'water which has been the closest of all, but still usually .2-.4 off every time. I have a calibrated mw102 (99% sure I am using it right), and do my reading at room temp. Here is a for instance from today

Brun'water, starting with RO with a ph of 6.4

water:
17 gallons of water treated for brewday, all liquor treated to 5.5ph (.27ml of phosphoric). This was also put in the water report input on brun.

Water built to:
52 mg/L Ca; 3 mg/L Mg; 8 mg/L Na; 17 mg/L SO4; 23 mg/L Cl; 80 mg/L HCO3; Residual Alkalinity = 30 mg/L HCO3

Grain bill:
10.5 pilsner malt
2.75 munich 10l
2.75 vienna
7oz acid malt (only added because I am ALWAYS higher than what the calcs say)

Now brunwater told me I would be at 5.2 and needed more alklinity, knowing what I have seen in the past I let it go. After my first rest, I took a reading, the reading came in at 5.38, which I called close enough to not mess with. This is the same trend I see with all water calcs.

Any ideas?

Thanks
Bryan

I've found the same issue with Bru'n water, but I don't mind because (a) it's usually off by the same amount each brew and (b) I have a pH meter. So long as the differential is relatively reliable and I'm able to measure it, I'm not concerned about it.

I've made enough brews with Bru'n water to know it's the best spreadsheet out there and pretty much always helps me zero in on my desired pH for whatever style I'm brewing.

One reason for the difference is that the pH of malted grain and distilled water will vary from maltster to maltster, year to year, etc. Another reason could be that your mash pH hadn't stabilized yet at the time you took your reading.

Thanks guys,

FYI my first rest is a 30 minute rest, I think pH has been set.

Its fine its off, but I feel bad for people who just use the sheet with out meters. Oh, and yes Brunwater is the best calc I have found.

Is that 17 gal of acid-treated water used for only the sparging or is that treated water used as the starting point for the mash water too?

I see that you're adding alkalinity. How is that being added to the mash water, what mineral?

Hey Martin,

The 17 gallons is mash and sparge water, and is used during all brewing related duties.

I added:

0.55 CaSO4

0.55g MgSO4

1.3g CaCl2

0.35g NaHCO3

2.7g CaCO3

Half of which is added directly to the mash, the other half being added to the kettle.

Bryan

The general answer to you question is that the spreadsheets model an extremely complicated system using simple models. They cannot, therefore, be expected to be too accurate. While they are good for planning, your comment about feeling sorry for people who use them without pH meters is significant. If you are going to try to control pH it is essential that you have a meter available to tell you whether you have succeeded or not.

In particular, you used calcium carbonate. There are 2 issues here. First, the spreadsheets do not (in what I have seen) model calcium carbonate accurately. Second, calcium carbonate reacts very slowly at normal brewing pH's. The good news is that you should never add calcium carbonate to brewing water unless you are willing to undertake the natural process by which it is found in natural water and that involves solution over time using carbonic acid (from CO2 gas). There is seldom, if ever a reason to do this. THe corollary to this is that you should not add calcium carbonate to mash either unless a pH meter reading shows that mash pH is too low. Of course this does not mean that you shouldn't add it to subsequent brews if a first brew showed it to be necessary. In that case you would determine the amount needed to get the mash pH right by experiment and then add that amount each time the beer is brewed, checking pH each time until you know what to expect and it's still a good idea to check pH then.