Bru'N Water vs BrewFather and BeerSmith3

Systems, Gear, & DIY
1

I created a vanilla Porter and each of the three software. However bru’n water gave 4.98 pH when BrewFather and BeerSmith gave 5.44.  Normally I use bru’n water for deciding how to treat my RO water but in this case I think it’s off. Any explanations why the difference?
input 2 row-base malt, caramel 40L-crystal malt, chocolate- roast, black patent-roast, munich light- base, roasted barley-roast.

Vanilla Porter-recipe
Water target- Brown Balanced. Ca50/Mg10/Na27/S70/C55/B90
RO water
Fermentables (12 lb 12 oz)
9 lb - Mash - Pale Malt 2-Row 2 °L (70.6%)
1 lb 8 oz - Mash - Caramel Malt 40L 40 °L (11…
1 lb - Chocolate 350 °L (7.8%)
12 oz - Mash - Black (Patent) Malt 369.7 °L (…
4 oz - Mash - Munich 7.9 °L (2%)
4 oz - Mash - Roasted Barley 300 °L (2%)
Hops (1.85 oz)
60 min - 0.25 oz - Chinook - 13% (11 IBU)
30 min - 0.6 oz - Tettnang (Tettnang Tettnage…
15 min - 0.5 oz - Perle - 8.2% (7 IBU)
5 min - 0.5 oz - Goldings, East Kent - 5% (2…
Miscellaneous
Mash - 0.18 g - Baking Soda (NaHCO3)
Mash - .96 g - Calcium Chloride (CaCl2)
Mash - 0.86 g - Canning Salt (NaCl)
Mash - 1.06g - Chalk (CaCO3)
Mash - 1.68 g - Epsom Salt (MgSO4)
Mash - .96 g - Gypsum (CaSO4)
Sparge - 0.96 g - Calcium Chloride (CaCl2)
Sparge - 0.86 g - Canning Salt (NaCl)
Sparge - 1.68 g - Epsom Salt (MgSO4)
Sparge - .96 g - Gypsum (CaSO4)
10 min - Boil - 0.1 oz - Irish Moss
10 min - Boil - 0.5 tsp - Yeast Nutrients
Yeast
1 pkg - Fermentis Safale American US-05

2

They use different models. Not sure what model Brewfather uses, but later versions of BeerSmith 3 allow you to choose between the old model (MPH-3) and BW, which I understand is the Bru’n Water model. MPH-3 is known to under-estimates the effect of acid additions.

Models are meant to get you into the ballpark and shouldn’t be used in the place of actual measurements.

3

I agree. This question comes up from time to time and it is simply a matter of using different models to calculate behind the scenes.

Have you brewed the Porter?

4

Furthermore, how the models compare depends on the recipe. For some recipes I see good agreement while for others they give wildly different predictions. My impression is that the agreement among models is better for very dark beers, where the acid contributions from roasted grains dominate. For very light beers the base malt dominates and that is highly variable between malts and models.