Why does my PH fluctuate so much?

Brewing Processes
1

I have been reading Palmer and Kaminski water book and am trying to wrap my head around it. My recent batch just confuses me. I know this is complicated but i would just like to be close to my predicted PH when i mash. I assume that its something to do with the Effective Alkalinity and Residual Alkalinity and the buffering capacity? I test my grain Distilled water PH and make necessary adjustments in EZ water along with using a proper PH meter with 2 pt calibration and room temp measurement.  This is my latest batch. Any suggestions on why my PH is way off.

Recipe: Recreational Real Ale TYPE: All Grain
Style: Specialty Beer
—RECIPE SPECIFICATIONS-----------------------------------------------
SRM: 21.1 SRM SRM RANGE: 5.0-50.0 SRM
IBU: 30.2 IBUs Tinseth IBU RANGE: 5.0-70.0 IBUs
OG: 1.045 SG OG RANGE: 1.030-1.110 SG
FG: 1.015 SG FG RANGE: 1.006-1.024 SG
BU:GU: 0.666 Calories: 151.6 kcal/12oz Est ABV: 4.0 %
EE%: 75.00 % Batch: 3.00 gal      Boil: 4.27 gal BT: 65 Mins

—WATER CHEMISTRY ADDITIONS----------------
Starting Water (ppm):
Ca: 66
Mg: 20
Na: 27
Cl: 18
SO4: 36
HCO3: 262

Mash / Sparge Vol (gal): 2.13 / 2.64
RO or distilled %: 25% / 25%

Total Grain (lb): 4.9

Adjustments (grams) Mash / Boil Kettle:
CaSO4: 0.4 / 0.495774648
CaCl2: 1.2 / 1.487323944
MgSO4: 0 / 0
NaHCO3: 0 / 0
CaCO3: 0 / 0
Lactic Acid (ml): 0.2

Mash Water / Total water (ppm):
Ca: 101 / 101
Mg: 15 / 15
Na: 20 / 20
Cl: 85 / 85
SO4: 55 / 55
Cl to SO4 Ratio: 1.56 / 1.56

Alkalinity (CaCO3): 132
RA: 51
Estimated pH: 5.69 My actual PH was 5.31 at 15 min
(room temp)

Total Grain Weight: 4 lbs 13.7 oz Total Hops: 0.75 oz oz.

-ADD WATER CHEMICALS BEFORE GRAINS!!<<<<<<<
Amt                  Name                                    Type          #        %/IBU       
4 lbs 1.4 oz          Pale Malt, Maris Otter (3.0 SRM)        Grain        1        84.2 %       
8.2 oz                Crystal, Medium (Simpsons) (55.0 SRM)    Grain        2        10.5 %       
4.1 oz                Carafa II (412.0 SRM)                    Grain        3        5.3 %

Name              Description                            Step Temperat Step Time   
Mash In          Add 2.13 gal of water at 169.2 F        154.0 F      60 min

—SPARGE PROCESS—

-RECYCLE FIRST RUNNINGS & VERIFY GRAIN/MLT TEMPS: 65.0 F/68.0 F
-ADD BOIL CHEMICALS BEFORE FWH
Fly sparge with 2.73 gal water at 168.0 F

—BOIL PROCESS-----------------------------
Est Pre_Boil Gravity: 1.033 SG Est OG: 1.045 SG
Amt                  Name                                    Type          #        %/IBU       
0.25 oz              Warrior [16.70 %] - Boil 60.0 min        Hop          4        30.2 IBUs

Amt                  Name                                    Type          #        %/IBU       
0.50 oz              Citra [13.00 %] - Aroma Steep 0.0 min    Hop          5        0.0 IBUs

2

5.3 is a normal mash pH. Maybe a tenth or two lower than you’d want for most beers.

So next time you’re brewing something fairly dark (5% Carafa is quite a bit), you could add a little alkalinity to the mash, or just not add the calcium salts, or not dilute, and you should be able to bump it up a bit.

I don’t think you’re doing your RA calculation correctly:

RA = TA - 0.71[Ca] - 0.59[Mg] = [HCO3]/1.22 - 0.71[Ca] - 0.59[Mg]

I get 156 (as ppm CaCO3) for the base water and 80 for the mash water as posted.

Edit: FWIW, I downloaded the EZ spreadsheet and it does calculate the RA correctly, so you may have an input error somewhere.

3

I suppose i am depending on an online calculator to aid in determining my PH, EZ water and there can be calculations that are wrong. I think in should lean how to do them manually like you have and it may help me understanding a bit more.  Also i though 5% Carfa was a bit much also i have never used that much. This is for a cask ale and found it in an old beer advocate mag. Thanks

4

You could always mash without the Carafa and cold steep it separately. Add the cold steep at the end of the mash. That way you mash will stay higher.