Bru'n Water pH predictions always about 0.1 too low -- how should I adjust?

[Horseflesh]

Bru'n Water very reliably gets me pretty close to my desired mash pH, but it's always 0.1 - 0.15 too low.

I assume that is about as good as it's going to get without taking any special steps to tune the process for the grains that your own LHBS provides. So my question is, what is the best way to fine-tune the prediction? If I assumed my predicted pH was always 0.1 too high that would be simple and pretty effective, but I am wondering if there is a more elegant or quantitative way to calculate a correction factor.

I'm also curious if the "fudge factor" might vary across the pH range, and how I might be able to figure that out.

Of course, the right answer might be to not worry about it, too.

 

[Silver_Is_Money]

You can play with the Lovibond colors of your grist bill, or play with the alkalinity of your water to compensate.

Is your problem that if you shoot for 5.4 as your mash pH via the software, you are actually measuring 5.5 to 5.55 pH in the mash at about the 10-15 minute mark, and for a room temperature sample? Or is it the other way around?

The difference you are seeing will not likely be uniform across the SRM color spectrum of various beers.

 

[Horseflesh]

If I adjust the colors, I wonder if there's a rule of thumb for how to adjust base versus crystal. Say I have majority 2L base malt with a little 60L crystal... I could probably match the actual mash pH by adjusting either or both. There's probably an optimal way to do it that will benefit the prediction accuracy in other batches too.

Hmm. I might have enough data points to do this. I can examine a hefeweizen (no dark malts) and figure out a correction for the base malts that makes the prediction correct. Then I can check a pale ale, assume a similar base malt correction, and make up the rest of the correction in the crystal malt.

 

[Silver_Is_Money]

I think you are on the right track. Base malts generally predominate, so altering the colors for those alone might be sufficient.

 

[mabrungard]

Assuming you are using a calibrated pH meter, it is most likely that the error you are witnessing is from the base malt. Most pale and pils malt will produce a wort pH of about 5.7 to 5.8 in distilled water. If your base malt is producing pH that is lower than that, then it is the culprit. Rahr 2-row pale malt has presented this problem to me in the past. Its possible that other malt could too. In the case of the Rahr product, I found that bumping the base malt color from 2 to 5 SRM (3 SRM increase) corrected the error.

The other thing that could alter your estimates is if your water's alkalinity is lower than you assume as the input. If the water source is variable, then you might need to have a home test kit for alkalinity to assess and correct for that variability.

 

[Horseflesh]

Thanks as always Martin! I'll fiddle with the base malt color. I should also check my water provider to see if they do seasonal changes.

 

[runningfarmer]

Briess two row is always off or low on ph but when I use Maris Otter its always spot on

 

[ScrewyBrewer]

I have had consistent pH results, two SMaSH batches four weeks apart, when mashing with Muntons Maris Otter and treated RO water, using a DIpH of 5.55. The calculated mash pH was 5.17 and the actual mash pH sample, taken 30 minutes into the mash and cooled to 70F, was 5.16.

 

[Silver_Is_Money]

I have had consistent pH results, two SMaSH batches four weeks apart, when mashing with Muntons Maris Otter and treated RO water, using a DIpH of 5.55. The calculated mash pH was 5.17 and the actual mash pH sample, taken 30 minutes into the mash and cooled to 70F, was 5.16.

It would be interesting to see the full recipe details for this batch, so we can understand how a single malt SMaSH with a DI mash pH of 5.55 results in a measured mash pH of 5.16. With moderate mineralization of the RO water, one would expect a mash pH not far below 5.55. Were you acidifying to intentionally hit a software predicted target mash pH of 5.17?

 

[ScrewyBrewer]

It would be interesting to see the full recipe details for this batch, so we can understand how a single malt SMaSH with a DI mash pH of 5.55 results in a measured mash pH of 5.16. With moderate mineralization of the RO water, one would expect a mash pH not far below 5.55. Were you acidifying to intentionally hit a software predicted target mash pH of 5.17?

For a 10 gallon batch the grain was 23 pounds Maris Otter Malt (UK) Muntons - DIpH=5.55. The water profile was 15 gallons of RO water treated with the following.

-- Mash water profile 15.0 gallons --
08.00 g - Gypsum (calcium sulfate)
15.00 g - Calcium Chloride
07.00 g - Epsom Salt (magnesium sulfate)
07.00 ml Lactic Acid
00.00 g - Baking Soda

The brewing water was then used to mash and sparge the grain and also top off the wort to hit the post-boil volume.

 

[Silver_Is_Money]

Might I ask why you were targeting 5.17 pH rather than the more common 5.4 pH? What are the potential benefits?

 

[Brewsncrabs]

I followed Martins Rahr 2row advice above and changed the lovibond to 5 as suggested. I had noticed Rahr always came up short and fudged it. Spot on this last brew! Thanks Martin!

 

[Silver_Is_Money]

The problem may be primarily one of base malt origin. It appears that base malts which originate in North America have lower DI mash pH's than do UK or European sourced base malts of the same Lovibond color rating (and in addition to this, fluctuations in DI mash pH may be seasonal, and/or more locally regional as well). I have a grab sample list of Breiss DI mash pH's (directly from Breiss), and their base malts DI mash pH's are quite low compared to base malts from UK/Europe (color for color).

Since most popular mash pH software does not ask the user for the origin of their base malts, or for actual DI mash pH's, and since the user would in most cases be unlikely capable of sourcing DI mash pH values reliably even if asked to input them, the programmer must default to an educated guess based solely upon color. But how is the program (I.E, the programmer) to know where your malts come from if all the program asks the user for is the malts color? Those users who claim that these kinds of programs can always get them within 0.1 pH of target (without knowledge of the base malts origin or actual DI mash pH's, or the ability to enter them) are merely blowing smoke.

And this hasn't even considered the potential for continental, national, regional, or seasonal differences in the DI mash pH's for caramel, crystal, and roasted malts. Nor does it consider that the various maltsters incorporate differing methods of malting which likely have an impact here as well.

 

[ajdelange]

A consistent error of .1 - .15 is called a bias error and is removed simply by subtracting 0.125 from each prediction. No need to fiddle with the malts or water unless you verify that one or the other of these is the source of the bias.