[TommyM]

I see acidulated malt in the grain bill of a lot of recipes.  I assume it is to lower the pH of the mash?

Wouldn't the amount used be completely dependent on the brewing system and water used? 

E.g. if the recipe calls for 2% acidulated, I may or may not need a different amount to achieve the desired pH.

[Robert]

I see acidulated malt in the grain bill of a lot of recipes.  I assume it is to lower the pH of the mash?

Wouldn't the amount used be completely dependent on the brewing system and water used? 

E.g. if the recipe calls for 2% acidulated, I may or may not need a different amount to achieve the desired pH.

You are absolutely correct.

[KellerBrauer]

It would also depend on the color of the grains used.  In other words, if you’re brewing a pale ale, for example, you would need more acid malt to lower the pH than you would if you were brewing a porter.  Some software, takes into consideration acid malt when entered into the grain bill.  This is assuming you would not be introducing any acid, i.e lactic, to the mash.

[Robert]

There's a neat little feature of the free advanced  water chemistry calculator at Brewer's Friend.   You can enter your water report, salt additions and grain bill, as well as acid additions, to calculate your pH.  (You can even specify a target pH and it will determine the amount of acid needed.)  Just choose lactic acid as the acid type.  Now, you could stop there, and just add the lactic acid, cutting out the middle man as it were, since acidulated malt is just malt coated in biologically produced lactic acid.   But here's the neat feature.   The final water profile report at the bottom of the calculator gives you an equivalent percentage of acid malt in the grain bill to your total lactic acid addition.   This must make some assumption about the acid content of the acid malt (it can vary a bit with manufacturer or batch) but this  would surely get you closer than just a random percentage from someone else's recipe.

[KellerBrauer]

I have been using the calculator in BeerSmith 3.  It seems to be a whole heap closer to “actual” than the previous version.  Then, on brew day, I measure my pH and add a little less than what BS3 recommends, then I measure again.  You can always add more, but you can never take away.

[Robert]

I have found the Brewer's Friend calculator absolutely dead on actual lately.  Which I cannot say for Bru'n Water anymore.  Don't know why.  Bru'n Water, at least the current  version, estimates a pH way lower than actual, and calculates a much smaller than actually needed amount of acid to shift pH a given amount (like when I try to use it to estimate my kettle addition -- I've gone back to doing that by hand, which gives me the exact right amount,  but it seems Brewer's Friend does something similar as I can just about use it to do the job.) 

[KellerBrauer]

I stopped using Bru’n Water quite a while ago.  It does way more than I need and it’s much more complex than I need.

[Silver_Is_Money]

The Weyermann  rule of thumb is that for every 0.1 pH points of drop you wish to achieve during the mash you need to add 1% by weight of grist as acidulated malt.

For example, if you mash a 13 lb grist and measure it at pH 5.7 and you want it to mash the next time at 5.4, you should add:

(13 * (5.7 - 5.4))/10 = 0.39 Lbs. of acid malt

0.39 x 16 = 6.2 ounces (rounded)

[narcout]

Bru'n Water, at least the current  version, estimates a pH way lower than actual, and calculates a much smaller than actually needed amount of acid to shift pH a given amount (like when I try to use it to estimate my kettle addition -- I've gone back to doing that by hand, which gives me the exact right amount,  but it seems Brewer's Friend does something similar as I can just about use it to do the job.)

That's interesting, I find that it estimates a pH that is usually slightly higher than actual (measured at the 20 minute mark) and that it overestimates the amount of acid malt needed (but you can adjust the acid malt strength setting to correct for that).

[Robert]

Bru'n Water, at least the current  version, estimates a pH way lower than actual, and calculates a much smaller than actually needed amount of acid to shift pH a given amount (like when I try to use it to estimate my kettle addition -- I've gone back to doing that by hand, which gives me the exact right amount,  but it seems Brewer's Friend does something similar as I can just about use it to do the job.)

That's interesting, I find that it estimates a pH that is usually slightly higher than actual (measured at the 20 minute mark) and that it overestimates the amount of acid malt needed (but you can adjust the acid malt strength setting to correct for that).

I used to get a different result too, it was usually a higher estimate than actual.  For some reason, that has changed.  No idea why.  I would have to go back through a lot more records than I  care to, to see just when it changed, and if there is any possible correlation to any other change in my materials or processes, or if it changed with the latest update to the program,  or maybe there's no clear indication.   From a practical standpoint, I just accept it, and adapt, or use the tool that works in a given instance.

[Big Monk]

Bru'n Water, at least the current  version, estimates a pH way lower than actual, and calculates a much smaller than actually needed amount of acid to shift pH a given amount (like when I try to use it to estimate my kettle addition -- I've gone back to doing that by hand, which gives me the exact right amount,  but it seems Brewer's Friend does something similar as I can just about use it to do the job.)

That's interesting, I find that it estimates a pH that is usually slightly higher than actual (measured at the 20 minute mark) and that it overestimates the amount of acid malt needed (but you can adjust the acid malt strength setting to correct for that).

One of the issues will always be that Sauermalz is a malt and works better modeled with the titration characteristics of a malt, not an equivalent amount of Lactic Acid. In fact, it’s treated with Sauergut, which further invalidates the mineral acid equivalence model.

https://www.homebrewersassociation.org/forum/index.php?topic=33238.msg424275#msg424275

https://www.homebrewtalk.com/forum/threads/how-do-i-convert-saurmalz-to-lactic-acid.665188/#post-8579361

[Aaron Winthrop]

I brew mostly grisette and saison style ales but even when I brew American styles like IPA and pales I include a .5 lb of acid malt instead of adding acid to the water or mash. I find it lends itself to be more smooth or natural tasting. Might just be my personal opinion, but even in the newer juicier IPA I think acid malt is a better option as opposed to actual acid adjustments. I have a triangle test done between the same beer made with acid malt vs lactic acid addition to mach and the one brewed with acid malt was strongly favored though no one was made aware of the difference.

[Robert]

Acid malt is fine for mash acidification.  But it cannot address either sparge acidification (where needed, as this is easily dispensed with by using deionized sparge liquor) or, more importantly, adjustment of wort pH in the kettle.  Since you will still need additions of acid at these stages of the process, I see no real advantage to using acid malt in the mash.  Using acid throughout simplifies things and makes the calculations easier all around.  My view.

[Big Monk]

Acid malt is fine for mash acidification.  But it cannot address either sparge acidification (where needed, as this is easily dispensed with by using deionized sparge liquor) or, more importantly, adjustment of wort pH in the kettle.  Since you will still need additions of acid at these stages of the process, I see no real advantage to using acid malt in the mash.  Using acid throughout simplifies things and makes the calculations easier all around.  My view.

I use acid malt because to me it’s easier and I don’t acidify in the boil. I also model it’s acid characteristics as malt and it gets crushed with my malt so it’s a no brainer.

Acid malt is a great option if you don’t need acid anywhere else in the process.

[Robert]

Acid malt is fine for mash acidification.  But it cannot address either sparge acidification (where needed, as this is easily dispensed with by using deionized sparge liquor) or, more importantly, adjustment of wort pH in the kettle.  Since you will still need additions of acid at these stages of the process, I see no real advantage to using acid malt in the mash.  Using acid throughout simplifies things and makes the calculations easier all around.  My view.

I use acid malt because to me it’s easier and I don’t acidify in the boil. I also model it’s acid characteristics as malt and it gets crushed with my malt so it’s a no brainer.

Acid malt is a great option if you don’t need acid anywhere else in the process.

Agreed.  I just don't see a need to use both in one brew.  I do acidify in the kettle, and I also don't have your kung fu with the calculations.  I can just about get it right if straight up mEq of acid is all I have to  come up with.