pH Measurements - What's Your Routine?

[H.Stiglitz]

Hello,
So I recently picked up a Milwaukee MW102 pH meter and I love it. No drift with consistent/repeatable results. Well, seems that way anyways.

My issue is timing my measurements with my mash. Currently, I take a sample at five minutes and put it in the freezer to chill to room temp. I collect only a small amount (maybe 20mL) in a 100mL beaker, but it still seems I'm taking my first reading between 10-15 minutes into my mash for any acid corrections. I feel like I'm slightly scrambling to. Does this delay even matter? Maybe I should put the beaker into an ice bath for faster cooling?

What is everyone's process for checking pH and acid additions.

Thanks.

 

[Bassman2003]

I take a reading 30 minutes into the mash and then make any adjustments. The adjustments are half for the next batch as taking the reading too early does not give you a clear picture imho. I have a little stainless steel type measuring cup set where I put cold water in the larger one and clip a smaller one sitting in the water holding the wort. Chills to 75F pretty quickly.

pH 5.4-5.6 for the mash then add a knockout addition down to pH 5.1 at 15 minutes left in the boil. If you use Whirlfloc, this great improves its performance.

 

[DBhomebrew]

Sounds like you may be trying to test pH in order to fix it in that batch.

Once the mash pH has stabilized enough to take a proper measurement, it's too late to do any meaningful adjustment for the batch in hand.

Many brewers here suggest testing mash 20m or so in and using that info for the next batch. Kind of like zeroing a rifle sight. Take a shot, see where it lands. Adjust sight, take another shot, etc. The adjustment is based on the prior shot and applied to next.

 

[Noob_Brewer]

agree here that hitting mash pH is reliant on previous batch experience familiarity with grain bill, recipe, and source water. Ive been acidifying my strike water and hitting mash pH where I want it which is typically in the 5.35 range for my IPAs. As for the boil though, Ive actually been acidifying my wort pre boil and not at knockout. For my IPAs which include several ounces of hops in the boil and whirlpool/steep, my knockout pH has landed at about 5.16-5.18 by acidifying wort pre boil only. What are the pros and cons of acidifying wort pre boil vs knockout or close such as the last 15 minutes of boil?

 

[jdauria]

5 minutes is a little early...15-20 minutes into mash is the norm. What I do is keep two shot glasses in the freezer, pull a small sample at 15 minutes, then pour it into one of the frozen shot glasses and swirl, then into the second shot glass and do the same...get the sample down to room temp in under a minute.

 

[Bassman2003]

agree here that hitting mash pH is reliant on previous batch experience familiarity with grain bill, recipe, and source water. Ive been acidifying my strike water and hitting mash pH where I want it which is typically in the 5.35 range for my IPAs. As for the boil though, Ive actually been acidifying my wort pre boil and not at knockout. For my IPAs which include several ounces of hops in the boil and whirlpool/steep, my knockout pH has landed at about 5.16-5.18 by acidifying wort pre boil only. What are the pros and cons of acidifying wort pre boil vs knockout or close such as the last 15 minutes of boil?

From what I have gathered, hop utilization and flavor is best in the 5.4 range.

 

[H.Stiglitz]

Sounds like you may be trying to test pH in order to fix it in that batch.

Nope. I've used BrunWater for years now and trusted it got me close to my pH target. I had a rather budget meter years ago it would show my pH being close enough to my target that was acceptable. I stopped taking any readings and got rid of that old meter a while ago. Well, I couldn't pass up the deal on this new pH meter and I figured I'd start doing regular pH measurements to verify and record my results. Just to get a little tighter on my process, and a new toy to play with.

However, I had to call an audible last weekend and change a recipe around last minute but I didn't change my calculated water additions. Measured pH at 5 minutes came to 5.6 - it added some lactic acid and got it down to 5.4.

What I do is keep two shot glasses in the freezer, pull a small sample at 15 minutes, then pour it into one of the frozen shot glasses and swirl, then into the second shot glass and do the same

This is a good idea to pre-chill the glasses. Maybe I'll try that next time. Thanks, this is more of what I'm asking. What is the process other's use to collect and measure samples at room temp?

I know from lurking here for quite sometime that the timing measurements will never be agreed upon and everyone does something different.

 

[Bassman2003]

Since you are new to the pH meter world, something I have learned is to keep your calibration solution up to date, calibrate every time you use the meter and to never reuse calibration solution. Fresh is key. I made a video about it on my brewing channel listed in my sig.

 

[H.Stiglitz]

Since you are new to the pH meter world, something I have learned is to keep your calibration solution up to date, calibrate every time you use the meter and to never reuse calibration solution. Fresh is key. I made a video about it on my brewing channel listed in my sig.

More like pH meter re-visited. I disagree with calibrating before every use especially with a decent quality meter like the MW-102. Kind of a subjective statement, don't you think? What if I use it daily, every other day, weekly, monthly, etc. Not everyone's usage will be the same. Milwaukee recommends after long storage or cleaning.

I've had this a couple months now and have calibrated it a few times, and after the first calibration the subsequent readings prior to re-calibration have been +/- 0.01 to the calibration solution.

 

[couchsending]

Cut a soda/beer can in half. Add enough wort to submerge the end of the probe, say 50ml. Use an ice water bath. Cools a lot faster than trying to use the cold air in your freezer. Metal also conducts heat/cold better than other materials. Metal cans are incredibly thin.

Wait 20-30 minutes before pulling a sample. As long as your mash ph is within 5.2ish to 5.55ish on the homebrew scale you’re fine. You won’t really see a huge change in efficiency. However if you’re using sparge water with any alkalinity and not adjusting it to a target pH I’d aim for the lower end of the mash pH range as you don’t want to extract tannins from the malt due to pH creeping up. Not as critical with higher ABV beers or darker beers but lower gravity pale beers it’s very important.

The pH of the boil can actually have a bigger impact on the final beer. There are all sorts of reactions occurring in the boil that have optimum pH values depending on the beer, ingredients, and what you’re trying to accomplish.

 

[marc1]

Cut a soda/beer can in half. Add enough wort to submerge the end of the probe, say 50ml. Use an ice water bath. Cools a lot faster than trying to use the cold air in your freezer. Metal also conducts heat/cold better than other materials. Metal cans are incredibly thin.

Wait 20-30 minutes before pulling a sample. As long as your mash ph is within 5.2ish to 5.55ish on the homebrew scale you’re fine. You won’t really see a huge change in efficiency. However if you’re using sparge water with any alkalinity and not adjusting it to a target pH I’d aim for the lower end of the mash pH range as you don’t want to extract tannins from the malt due to pH creeping up. Not as critical with higher ABV beers or darker beers but lower gravity pale beers it’s very important.

The pH of the boil can actually have a bigger impact on the final beer. There are all sorts of reactions occurring in the boil that have optimum pH values depending on the beer, ingredients, and what you’re trying to accomplish.

Some people on Reddit seem to be acidifying NEIPAs to mid to high 4s post-boil - what's your take on that?

 

[Bassman2003]

More like pH meter re-visited. I disagree with calibrating before every use especially with a decent quality meter like the MW-102. Kind of a subjective statement, don't you think? What if I use it daily, every other day, weekly, monthly, etc. Not everyone's usage will be the same. Milwaukee recommends after long storage or cleaning.

Sorry, I was in a hurry and it was not the best statement. I calibrate mine if two weeks have gone by since the last calibration. I usually do not brew more than once in that time period. World through our own eyes... I did not realize things had to be so serious. This will be my last input on your topic.

 

[H.Stiglitz]

Some people on Reddit seem to be acidifying NEIPAs to mid to high 4s post-boil - what's your take on that?

Interesting. Haven't tried anything too outlandish with end of boil pH. Anyone with first hand experience doing this?

 

[mabrungard]

Mashing pH does vary by several tenths during the mash. I find that it’s relatively stable after about 45 minutes into the mash. This is why it’s important to use software to estimate your wort pH with the planned adjustments and generally let the mash progress. Monitoring and chasing pH based on early measurements is unwise.

Regarding wort chilling, I used to use frozen shot glasses and that works, but the wort can get too cool and that’s not good either. I’ve switched to stainless steel shot ‘glasses’ placed in an ice water bath. That works well and I generally don’t chill too much.

You do want the wort temperature in the 20 to 25C range for a representative measurement.

 

[Deadalus]

Mashing pH does vary by several tenths during the mash. I find that it’s relatively stable after about 45 minutes into the mash. This is why it’s important to use software to estimate your wort pH with the planned adjustments and generally let the mash progress. Monitoring and chasing pH based on early measurements is unwise.

Regarding wort chilling, I used to use frozen shot glasses and that works, but the wort can get too cool and that’s not good either. I’ve switched to stainless steel shot ‘glasses’ placed in an ice water bath. That works well and I generally don’t chill too much.

You do want the wort temperature in the 20 to 25C range for a representative measurement.

Something like this? We always called them "bullets" years ago in the restaurant I worked at but can't remember if that was common to restaurant lingo. Sauce cup. PITA to run through the dishwasher and about as much fun as a bunch of Legos on the living room floor.

 

[H.Stiglitz]

This is why it’s important to use software to estimate your wort pH with the planned adjustments and generally let the mash progress.

Thanks. I've been using your BrunWater for years with great success. It's only my new fancy equipment that has got me trying to do better with my data logging. I read an article recently on byo talking about probe degredation above room temps, as well as understanding that the pH will change with temps changes in sample.

So, with the pH fluctuations during the first majority of the mash would you even try to correct it if for some reason you calculated wrong? Like my last batch where I altered the grain bill last minute, but didn't change my water additions.

 

[H.Stiglitz]

Sorry, I was in a hurry and it was not the best statement. I calibrate mine if two weeks have gone by since the last calibration. I usually do not brew more than once in that time period. World through our own eyes... I did not realize things had to be so serious. This will be my last input on your topic.

Hard to read tone through text. I apologize if my disagreement caused any anguish. No need for dramatics.

 

[marc1]

Thanks. I've been using your BrunWater for years with great success. It's only my new fancy equipment that has got me trying to do better with my data logging. I read an article recently on byo talking about probe degredation above room temps, as well as understanding that the pH will change with temps changes in sample.

So, with the pH fluctuations during the first majority of the mash would you even try to correct it if for some reason you calculated wrong? Like my last batch where I altered the grain bill last minute, but didn't change my water additions.

What I would do if I realized after mashing in that the grain bill was different than used to calculate the additions is re-work the additions in the software. It only takes a couple of minutes, especially with the previous work saved already to update. I would then add more lactic or baking soda, whichever was needed to bring it where I wanted it. Stir it in well, then measure near the end of the mash as normal.

I'm sure there are other ways of addressing it, though.

 

[Bassman2003]

Hard to read tone through text. I apologize if my disagreement caused any anguish. No need for dramatics.

Disagreement is great. I just thought it was kind of rude. Just trying to help. No worries. Storm in a stainless steel teacup.

 

[Silver_Is_Money]

Clearly (and also, logically) the most perfect time to gauge the mash pH for a 60 minute mash would be to measure pH at the 60 minute mark of the mash, but I'm open to the conception that after 45 minutes of mashing any additional pH change should be minimal/minimized, albeit with the caveat that one need not chance such a presumption to be true when it is just as easy to sample at 60 minutes as it is for sampling at any other (potentially premature) time.

But that's only part of the story. To get an honest pH reading requires that:
1) Calibration is done at 20 or 25 degrees C. (meter instruction dependent), and completed not long before actual sample measurement, and to within acceptable stability/repeatability.
2) The sample is checked at the very same 20 or 25 degrees C. (meter instruction dependent)
3) The pH probe is rested in the sample (and/or calibrants) for at least 1 minute with zero stirring (which induces a false low reading due to what is referred to as "stirring error"). Thank you @dmtaylor ** for first bringing this false low stirring pH observation to our attention, and AJ deLange ** for quantifying and better detailing its impact for us.
4) pH meters "stability" indicators are notorious for coming on far and away much too early. (a subset of #3 above)

Virtually every error one can possibly make when taking a pH reading (including inadequately cleaning and maintaining the probe) will shift the outcome to one that is demonstrably lower than the actual pH. Those who routinely make a hobby out of scoffing at certain of mash pH prediction software that generally tends to give somewhat higher pH predictions (when compared to other/favored software of its ilk) should take careful note here and reflect deeply upon the implications of their judgement.

** @dmtaylor mentioned in one of his posts several years ago that regardless of which pH meter he was using, each time he stirred his pH probe around in his sample the pH went down appreciably. AJ subsequently explained why, and defined it as "stirring error". And AJ subsequently mentioned as to why so many readings are grossly in error to the low side as a consequence.

 

[couchsending]

Some people on Reddit seem to be acidifying NEIPAs to mid to high 4s post-boil - what's your take on that?

I think that’s excessive and unnecessary. I’d like most people use use some variation of 1318 and you pitch enough yeast it will lower pH to almost 4.0 on its own. Lowering KO ph to such low numbers with either lactic or phos Could have a flavor impact as especially with large WP hop amounts it can take quite a bit of acid. No real reason to go below 5.0.

 

[marc1]

I think that’s excessive and unnecessary. I’d like most people use use some variation of 1318 and you pitch enough yeast it will lower pH to almost 4.0 on its own. Lowering KO ph to such low numbers with either lactic or phos Could have a flavor impact as especially with large WP hop amounts it can take quite a bit of acid. No real reason to go below 5.0.

Yeah, I didn't see a good explanation as to why, and it seemed shockingly low. But was curious if anyone here with good knowledge for the style had anything good to add about it.

 

[dmtaylor]

** @dmtaylor mentioned in one of his posts several years ago that regardless of which pH meter he was using, each time he stirred his pH probe around in his sample the pH went down appreciably. AJ subsequently explained why, and defined it as "stirring error". And AJ subsequently mentioned as to why so many readings are grossly in error to the low side as a consequence.

Carbon dioxide in the ambient air will dissolve to form carbonic acid at low concentrations. Unfortunately, carbonic acid is, of course, acidic, so the pH will always drop. I suppose you could stir to your heart's content if you could do so in an atmosphere of pure nitrogen or in a vacuum.

 

[CascadesBrewer]

Does it matter how much grain is in the sample for a pH reading? I guess I need to try it both ways on a batch, but I feel like I get a more stable reading when I take a sample from outside my brew bag so it has very little grain, vs a sample from inside the grain bag where I am bound to get some grain. It could also just be an issue with my $40 pH meter. I guess I also need to try the "1 minute with zero stirring" process.

most perfect time to gauge the mash pH for a 60 minute mash would be to measure pH at the 60 minute mark of the mash

I tend to take a reading at 30 minutes, and also stir my BIAB mash. That statement makes me wonder...if the vast majority of conversion happens in the first 20 minutes, wouldn't the mash pH at that time be more important, at least for conversion in the mash?

 

[day_trippr]

20, 40 and 60 minute checks, then an end-of-sparge check, then a full pre-boil pH check, then an end-of-boil pH check.
Almost all of that is just data collection in case there's ever some reason to look backward - and of course if something is off to fix the recipe for any repeat batches.

I don't chase pH...

Cheers!

 

[CascadesBrewer]

20, 40 and 60 minute checks, then an end-of-sparge check, then a full pre-boil pH check, then an end-of-boil pH check.

Do you check pH further along in the process? I feel like I should at least check pH of the finished beer (before carbonation?) but I am not sure what I would do with that data (or if I could trust the data from my pH meter enough to do anything).

 

[Silver_Is_Money]

As to sitting the pH probe undisturbed, it is the highest stable pH reading that is to be preferred. A bit of probe stirring upon placing the probe into the sample is required whereby to properly/uniformly wet the probe in the sample. After that let the probe sit undisturbed until the pH reading stops rising. If (for example) mild stirring yields a pH of 5.31, and after a long wait with the probe at rest in the sample the reading finally settles in at 5.48, then the pH is 5.48.

The last thing anyone should want to do is to manipulate the pH reading (stir, impulsive snap-shot (mentally or via camera), etc...) whereby to bring it into better (or worse, perfect) conformance with a pre-conceived pH target as derived via ones 'chosen' pH prediction software. That is just pure bias at work. AJ deLange labeled it "Confirmation Bias". But sadly, for many, achieving just such conformance is the first thing they desire to do.

It used to make me giggle whenever I viewed the obligatory snap-shots (taken by a popular triangle-test oriented group) of mash pH's precisely verifying software predictions literally every time. Don't get fooled into worshiping at the alter of mash pH software. Mine included.

Edit: The actual last thing anyone should ever want to do is to abandon pH readings altogether since worshiping at the alter of pH software has led to the belief that god-like software is superior to mere mortal and thereby subject to being flawed pH readings. Another thing that amuses me is when I read something along the lines of "I stopped taking pH readings years ago when I VERIFIED that software-X was ALWAYS spot-on". Part of my amusement comes from the knowledge that all of such software evolves and changes with time, and as a consequence (of intended continual improvement) current versions do not output the same pH predictions as do earlier versions. It seems that the hidden desire here is to subliminally brainwash people into a belief that there is no need to ever again bother with pH because pH prediction Nirvana has been achieved by software-X (... years ago, no less ...).

 

[H.Stiglitz]

Thanks for the responses. Maybe with my new meter I felt obligated to use it as much as possible. Usually I don't adjust anything after I mash in and the software gets me very close to my target. On this last batch I kind of had a faux pas, I suppose.

3) The pH probe is rested in the sample (and/or calibrants) for at least 1 minute with zero stirring (which induces a false low reading due to what is referred to as "stirring error"). Thank you @dmtaylor ** for first bringing this false low stirring pH observation to our attention, and AJ deLange ** for quantifying and better detailing its impact for us.

Very interesting. Didn't know that. Makes sense though and I do give it a good stir to try to knock any bubbles off. I shall stop. Haha

 

[Silver_Is_Money]

Very interesting. Didn't know that. Makes sense though and I do give it a good stir to try to knock any bubbles off. I shall stop. Haha

You were likely typing this at the very same time as I was typing my post above. A bit of stirring initially has benefit. Don't stop.

 

[H.Stiglitz]

You were likely typing this at the very same time as I was typing my post above. A bit of stirring initially has benefit. Don't stop.

Haha. Yes. Indeed. I shall resume.

 

[couchsending]

Stirring is fine. Need to homogenize the sample. If your meter is very slow to get to a stable number you most likely need a new probe. A reading should stabilize rather quickly.

Highly suggest the Milwaukee 101 or 102 meters. Best bang for the buck.

If you’re fermenting in a vessel where taking samples is easy (stainless conical) checking pH during fermentation can also tell you a lot about the vitality of your yeast.

 

[chilitom]

I use a thin-walled disposable plastic cup. I withdraw ~50 ml into the cup, then swish it around in an ice bath. It takes maybe 30 seconds to bring it down to room temperature. I use one of the handheld pH meters and find that if I SLOWLY move it back and forth in the sample I get the most stable readings. Also, I calibrate it just before using it every time. I use the little buffer powder pillows from Hach that make up 50 ml of buffer solution, so I always have fresh buffer solutions for calibration. I have like 100 of these that will last years.

 

[day_trippr]

Do you check pH further along in the process?[...]

Nope, I have never tested anything post-fermentation...

Cheers!

 

[BrewDrinkRepeat]

I also agree 100% that by the time you take a pH reading, it's far too late to do anything about it in terms of the mash (although you could make adjustments intended to influence the flavor of the finished beer -- I don't, but I'm not saying it should never be done).

Use that data for the next batch of that recipe, and then RDWHAHB.

I don't always even bother to take a measurement, but when I do it's no earlier than the 30 minute mark, and more often than not I end up doing it right before I lift the grain basket. (I'm a no-sparge Foundry brewer these days.) Again, I'm using it as a reference measurement, not an actionable one.

I use Bru'n Water and a Hach Pocket Pro+, and like many I've found the estimated pH to be well within the "close enough" range for me, rarely varying from the meter by more than 0.1 or so. I design my water additions to hit a specific pH, but if I miss by a little I just don't worry about it.

If I was shooting for 5.4 and got 5.5 or 5.3, that doesn't bother me in the least, and the effect on the finished beer is negligible for the most part. I might make a compensation adjustment for next time, or I might not. And I certainly don't make that decision until I've fully evaluated the finished beer.

Here's my take on mash pH in general: it is (of course) an important metric in the brewing process, but as long as you are in the generally-accepted mash range (5.2 - 5.6, maybe 5.8 for very dark roasty malty beers) the exact pH is far less important to the finished beer than getting the flavor components of the water chemistry correct.

Missing your pH by a tenth or even two may be noticeable, but hardly catastrophic and the batch will certainly not be ruined in any way; get your water chemistry wrong and the finished beer could be significantly off the mark, especially for bitter and/or very malty styles.

 

[balrog]

I take a 50ml syringe sample at 30m stir time and set aside to measure when cool.
My biggest diff between predicted and measured are lighter SRM beers, biggest overall diff when doing recipe with 40-50% wheat.

 

[Deadalus]

I take a 50ml syringe sample at 30m stir time and set aside to measure when cool.
My biggest diff between predicted and measured are lighter SRM beers, biggest overall diff when doing recipe with 40-50% wheat.
View attachment 744815

Good data there balrog.

Which are the two calculators in the legend? What does the rest of the data (higher than 9 SRM) look like? MME is not particularly heterogenous...there are more observations in the 3-5 range than at 7.5-9 (just three brews), could just be missing more extreme residuals there. A confidence interval on the mean of the residuals (bias) would be informative. BF has some potential outliers around 3 SRM. Is it possible they are related in some fashion, same recipe for instance?

There's an accuracy to the pH meter used but there's also model accuracy of the calculator. They just spit out a value right but if they are built from real world observations there's a prediction accuracy too.