Author Topic: Mash Acid addition calculator way off for BS3  (Read 3875 times)

Offline foxie22

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Mash Acid addition calculator way off for BS3
« on: June 24, 2018, 12:54:01 AM »
So I have been using Bru'n water to calculate my acid additions with great success. However I purchased Beer smith 3 so I could cut down time and just use the one program to do all of the calculations. But the calculations the program are giving me are just ridiculous ! the calculation BS gives me is- for a 25.5L mash with alkalinity of 84.4 - I will require 9.2 ml of 96% phosphoric acid to drop the mash Ph from  5.67 to 5.2. Where as in Bru'n water if I was to add 9.2ml of 98% phosphoric acid to the 25.5L mash it gives me a calculated mash ph of  4.21. I am just wondering if who ever has come up with these calculations has even tested the theory practically? I know Bru'n water's calculations are correct because i have tested them with a Ph meter and found them to be very accurate.

Has anyone else found this to be the case ?

Cheers

Luke

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Re: Mash Acid addition calculator way off for BS3
« Reply #1 on: June 24, 2018, 03:04:11 PM »
BNW ignores the acid density which has a particularly large effect when using phosphoric acid.  I've discussed this in other threads, but the here's a comparison of the models (page 7).  BeerSmith uses the model described in the paper which does include the effects of acid density:
  https://www.dropbox.com/s/vkc2smfhbd1705e/Effect%20of%20Water.pdf?dl=0

 If you go to page 7 you will see the acidity delta in the table changes pretty dramatically with BNW for phosphoric, meaning it will calculate a lot less phosphoric.  In fact it calculates almost double the acidity change (which means half the acid needed) for the particular comparison case with phosphoric that the other water tools or models did.  This is a pretty significant problem with BNW - not the other tools.

I've already had a number of people ask me why didn't I just make my model match the BNW (or EZ Water, or KW or pick your favorite tool)? 

If you read the paper and understand the chemistry involved, you will see why the other models have problems and why I went with the one I did.  When using any model, I do the research first and pick the best one I can find which I did in this case.

That being said - these are models folks.  In the real world a lot of factors come into play that we don't really know including the actual acidity of each grain addition, the precise composition of your water, crush of the grain, etc... so I always recommend actually measuring your mash pH and adjusting again if needed.

Brad
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Online GigaFemto

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Re: Mash Acid addition calculator way off for BS3
« Reply #2 on: June 24, 2018, 06:06:53 PM »
That being said - these are models folks.  In the real world a lot of factors come into play that we don't really know...

Yes, definitely. I have been using BNW, and was getting accurate results using the lactic acid additions that it recommended. Then earlier this year I began to find that my mash pH was too high. Possibly my lactic acid has degraded despite being kept in the fridge. Most likely my water changed a bit and I have had to compensate by adding more acid than BNW specifies. Or possibly the batch of grain I got was different than the previous one, or perhaps.....

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Offline Jppsav

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Re: Mash Acid addition calculator way off for BS3
« Reply #3 on: July 14, 2018, 07:52:31 PM »
My first brew with BS3 and I found the acid calculation to be very close. BRnW estimated 3.41 ml of LA and BS estimated 7.2. Actual adjustment required 8.2. This was for a 10 gallon batch.

Offline Javaslinger

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Re: Mash Acid addition calculator way off for BS3
« Reply #4 on: July 27, 2018, 07:42:11 AM »
BNW ignores the acid density which has a particularly large effect when using phosphoric acid.

Bru'n Water employs a full set of acid density vs strength curves for each liquid acid available in the program. The paper cited is over 5 years old and Bru'n Water did have an error in acid densities vs strength at that time. It has long been corrected.

I would love to see a survey on what the industry is using for mash pH adjustments.  I know a half dozen pro brewers personally and they swear by Bru n' Water.  You probably know a lot more.  How many are not using Bru n' Water?   

Offline Oginme

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Re: Mash Acid addition calculator way off for BS3
« Reply #5 on: July 27, 2018, 08:45:06 AM »
You can see my analysis of a pilsner recipe which I had brewed a couple of times and measured pH with and without  acidulated malt on this thread: http://www.beersmith.com/forum/index.php/topic,18828.0.html

Overall, it seems like all of the water adjustment tools are lacking somewhat when it comes to the use of acidulated malt.  In the end, I calculated that increasing the acid content value of the malt to a little above 3% brought the pH prediction from BeerSmith into alignment with my actual results.  At this same acid content of the malt, Bru'n water ended up well below my actual results.  There does seem to be a difference with the way they calculate the acid contributions, but neither is really too far off the mark that it is unusable.  My main issue is the wide range of pH results from base malts in general and the programs sort of lumping them all into one category.  I currently have a few pounds of several base malts that I plan on doing some testing on to see how much scatter there is in their contribution to mash pH.  Likewise, my data sense indicates that making a straight line regression for caramel/crystal malts introduces another error into the mix.  It is a slight error, but they all tend to add up after a while.  The plot of roasted malt pH versus color looks more like a scatter diagram, which may be indicative of the base malt used or process differences in the kilning/roasting.
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