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BS3 acid additions don't agree with Bruh'n Water

tdx

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I'm not a water expert, so I'm not sure how to validate the new water addition features of Beersmith 3.0.  I figured comparing it to Bruh'n Water should be a decent evaluation though.

With just straight minerals and salts both agree my mash ph will be 5.56.  When I add 5.8ml of lactic acid, per Beersmith's calculated suggestion to get a ph of 5.2, they don't agree.  Bruh'n Water says my mash ph will be 5.12 instead of the 5.21 Beersmith calculated it to be.

I've gone over this many times trying to figure out if I entered something wrong.  My water report is the same in both, I've entered the same grain bill, the same mineral/salt additions, volumes match and yet the lactic acid calculations are not the same.  Bruh'n Water indicates I should add 4.6ml of lactic acid instead of 5.8.  Is anyone else seeing this issue? 
 

BeerSmith

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Here's a detailed analysis if you want to know the exact reason why:
  https://www.dropbox.com/s/vkc2smfhbd1705e/Effect%20of%20Water.pdf?dl=0

BeerSmith uses the method outlined in this paper which includes the effects of acid density.  I believe BNW does not fully account for this.  You can see a comparison of the values resulting near the end of the paper.

Brad
 

Oginme

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tdx said:
When I add 5.8ml of lactic acid, per Beersmith's calculated suggestion to get a ph of 5.2, they don't agree.  Bruh'n Water says my mash ph will be 5.12 instead of the 5.21 Beersmith calculated it to be.

I just want to put this into perspective with regard to models versus real life.

The models show a difference of .09 pH units.  Most pH meters being used by home brewers are not even that accurate.  The Milwaukee MW802 pH meter has an accuracy of +/- 0.02 units, most other meters are no better than +/- 0.1 pH units accuracy.  That is before anyone factors in accuracy of calibration. 

The fact that two models based upon different data sets come in within that margin of error is pretty darn good. 

Unless you measure your mash pH in a real situation, you have no way of knowing which model is best representing your process and raw materials.  Even then, given the minor difference in outcome and the error band around the instrument you are using you will still be in a good range for the conversion enzymes to operate very effectively regardless of which recommendation you start with.

I can tell you with experience, that I skew my target pH based upon the specific base malt that I m using.  If I am using my standard Rahr 2-row malt, I will target the model for 5.5 pH and will typically end up at 5.2 to 5.5 pH.  On the other hand, If I am using Crisp Maris Otter, I will be targeting 5.1 to get to a pH range of 5.2 to 5.4.  All those ranges are perfectly fine for conversion of the starches into sugars.  BTW, this happens in both Bru'n Water and in BeerSmith.  I do my adjustments by using acidulated malt or occasionally a bit of acid into the strike water.  Once I've mashed in, I don't sweat the reading unless I am far outside the sweet spot of 5.2 to 5.6 pH.


 

Javaslinger

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I have always measured my pH 20 minutes in the mas and found Bru n' Water to be spot on.  I don't care what model Beersmith 3 is using, but if it's asking me to add considerably more acid that Bru n' Water, I'm not only skeptical, but not terribly happy.  This is the #1 improvement I was hoping to come out of Beersmith 3. 

I would like to see some data that occured during beta testing of Beersmith 3 to lend some validity to the model, rather that just saying we think our model is better.  Nearly every serious brewer I know uses Bru n' Water and it is thoroughly validated.
 

BeerSmith

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Javaslinger said:
I would like to see some data that occured during beta testing of Beersmith 3 to lend some validity to the model, rather that just saying we think our model is better.

If you take a look at the chemistry in the paper, you will see the problem with ignoring acid density.  I try very hard to base all of the equations used in BeerSmith on the latest brewing chemistry, physics and data I can find.  I'm a scientist at heart, so ignoring the latest research to match someone else's tool or spreadsheet is not how I approach the problem.  In fact if I can find a better model tomorrow for estimating mash pH or calculating acid additions, I'll probably try to work it into the next edition of BeerSmith.

Keep in mind that any of these tools are based on models, and they may or may not match your actual numbers when it comes to a particular brewing system, water profile and grain bill.  Your mash pH may be spot on for one recipe and off in another.  That's why I always recommend measuring if you have the equipment.

That being said if you like another tool, then by all means continue to use it.  If you would like a refund on BeerSmith 3 just let me know.

Brad
 

dsc123

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Brad, in case you hadn't seen it, I just wanted to point out this post by the author of the paper you cited.  https://www.homebrewtalk.com/forum/threads/beersmith-3-ph-tool.653778/page-2#post-8512571

Thanks for making a great program
 

dsc123

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Man, I really did look before posting that too.  :-[

Didn't want to seem like I was piling on--I love BS3.
 
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