Silver_Is_Money
Larry Sayre, Developer of 'Mash Made Easy'
Givens:
15L or 30L of DI mash Water, with this DI water at pH 7.00
6 Kg. Grist
Aggregate grist buffer = 45 mEq/Kg.pH
Aggregate pHDI of the grist = 5.65
Target pH = 5.40
88% Lactic Acid at pH 5.40 has an acid strength of 11.451 mEq/mL
For brevity in what is already going to get long you're going to have to trust me on these two pre-calculated givens:
1) mEq's of acid required to move 15L of 7 pH DI water to pH 5.4 = 0.05822
2) mEq's of acid required to move 30L of 7 pH DI water to pH 5.4 = 0.11643
mEq's of acid required to move the grist alone to pH 5.4:
Delta_pH = (5.65 - 5.4) = mEq's/(45 x 6)
mEq's = 67.5
3) mEq's required to move 15L of DI + the Grist to pH 5.4
= 67.5 + 0.05822 = 67.55822
4) mEq's required to move 30L of DI + the Grist to pH 5.4
= 67.5 + 0.11643 = 67.61643
Lets 1st assume that our software simply ignores DI water volume in the mash and calculates thereby that:
67.5/11.451 = 5.89468 mL of 88% Lactic Acid addition called for to hit pH 5.4
Let's next assume that our software adds in the water for 15L:
67.55822/11.451 = 5.899766 mL of 88% Lactic Acid addition called for to hit pH 5.4
Let's lastly assume that our software adds in the water for 30L:
67.61643/11.451 = 5.904849 mL of 88% Lactic Acid addition called for to hit pH 5.4
For the 15L mash water case our software that ignores water volume completely shorts the lactic acid addition by:
5.899766 - 5.89468 = 0.005086 mL
0.005086 x 11.451 = 0.05824 mEq's
For the 30L mash water case our software that ignores water volume completely shorts the lactic acid addition by:
5.904849 - 5.89468 = 0.010169 mL
0.010169 x 11.451 = 0.11644 mEq's
For the 15L mash volume our software's pH error is therefore:
Delta_pH = pH_error = 0.05824/(45 x 6)
pH_error = 0.000215704 pH points
For the 30L mash volume our software's pH error is therefore:
Delta_pH = pH_error = 0.11644/(45 x 6)
pH_error = 0.00043126 pH points
Conclusion. Due to strong grist buffering vs. nill DI water buffering a mashes water volume can safely be ignored by software, as for our above examples the maximum error induced by ignoring the water is 0.00043 pH points. It is only that which is in the water that actually matters. The water itself does not. And technically all water can be considered to be DI water plus added minerals, whether added by mother nature or by the brewer. And the software only needs to consider the minerals and the grist, and not the water.
15L or 30L of DI mash Water, with this DI water at pH 7.00
6 Kg. Grist
Aggregate grist buffer = 45 mEq/Kg.pH
Aggregate pHDI of the grist = 5.65
Target pH = 5.40
88% Lactic Acid at pH 5.40 has an acid strength of 11.451 mEq/mL
For brevity in what is already going to get long you're going to have to trust me on these two pre-calculated givens:
1) mEq's of acid required to move 15L of 7 pH DI water to pH 5.4 = 0.05822
2) mEq's of acid required to move 30L of 7 pH DI water to pH 5.4 = 0.11643
mEq's of acid required to move the grist alone to pH 5.4:
Delta_pH = (5.65 - 5.4) = mEq's/(45 x 6)
mEq's = 67.5
3) mEq's required to move 15L of DI + the Grist to pH 5.4
= 67.5 + 0.05822 = 67.55822
4) mEq's required to move 30L of DI + the Grist to pH 5.4
= 67.5 + 0.11643 = 67.61643
Lets 1st assume that our software simply ignores DI water volume in the mash and calculates thereby that:
67.5/11.451 = 5.89468 mL of 88% Lactic Acid addition called for to hit pH 5.4
Let's next assume that our software adds in the water for 15L:
67.55822/11.451 = 5.899766 mL of 88% Lactic Acid addition called for to hit pH 5.4
Let's lastly assume that our software adds in the water for 30L:
67.61643/11.451 = 5.904849 mL of 88% Lactic Acid addition called for to hit pH 5.4
For the 15L mash water case our software that ignores water volume completely shorts the lactic acid addition by:
5.899766 - 5.89468 = 0.005086 mL
0.005086 x 11.451 = 0.05824 mEq's
For the 30L mash water case our software that ignores water volume completely shorts the lactic acid addition by:
5.904849 - 5.89468 = 0.010169 mL
0.010169 x 11.451 = 0.11644 mEq's
For the 15L mash volume our software's pH error is therefore:
Delta_pH = pH_error = 0.05824/(45 x 6)
pH_error = 0.000215704 pH points
For the 30L mash volume our software's pH error is therefore:
Delta_pH = pH_error = 0.11644/(45 x 6)
pH_error = 0.00043126 pH points
Conclusion. Due to strong grist buffering vs. nill DI water buffering a mashes water volume can safely be ignored by software, as for our above examples the maximum error induced by ignoring the water is 0.00043 pH points. It is only that which is in the water that actually matters. The water itself does not. And technically all water can be considered to be DI water plus added minerals, whether added by mother nature or by the brewer. And the software only needs to consider the minerals and the grist, and not the water.
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