pH Strips Make me Angry - Need Help

I finally decided to start actually monitoring my pH in my mash with my latest batch of Centennial Blonde. I have always just assumed that the EZ Water spreadsheet was correct and I would add the appropriate amounts of acid to get me in the 5.4 - 5.6 pH range. This has given me good results in the past but as most of you know, we always want to see if we can improve a little more if possible so I wanted to just make sure my pH ranges were correct.

After buying a pack of the brewing pH strips from my LHBS, I did a reading on my tap water and it seemed to be at 6 pH or higher (only able to test up to 6). I figured this was a good sign and that I could trust these strips a little for my upcoming brew day.

Brew Day:

Based on EZ Water I was planning to add 3ml of Lactic Acid to get my pH down from 5.64 to 5.47 (room temp) BUT after adding my brewing salts (which should have little impact on pH) to my mash, I tested and the strips seem to show that my pH was actually around 5 or even a tad lower so I didn't add any of the Lactic Acid. I was still debating adding some acid because this just didn't jive with the EZ Water spreadsheet I had setup but I held off thinking I could trust the pH strips.

My efficiency was great and things went as normal but I am looking to see if anyone can provide me some feedback on how accurate the EZ water spreadsheet is and if I should even bother with trying to test my pH. I would rather not buy a pH meter and have to hassle with the buffering and stuff that goes along with it. I just feel like the EZ Water and Brun Water spreadsheets are pretty solid and if you can provide a good profile of your water report, they should get you very close based on all of your inputs but maybe I am being naive.

Any thoughts?

The first thing I'd suggest you do is put some identical numbers into both spreadsheets and see if you get the same pH predictions. You won't. So which is right? Who knows? The only way to find out is to brew the beers and measure the pH using proper technique and equipment. Spreadsheets are based on models and the models require accurate data. To get accurate data for a mash pH prediction one must do an elaborate, time consuming set of measurements on each malt used in the grist and when I say each malt I don't mean that I can run Weyermann's Pils and put the data on a website. I mean the lot of Weyermann's Pils that you are going to use for your particular brew. It is much, much easier to take a portion of the grist you intend to mash and mix it with a small amount of the water you are going to use and measure the pH of that. This will give you a good prediction of the actual mash pH but even then it won't be spot on. Part of the problem is that pH drifts over time. The question you need to ask of any spreadsheet developer is 'pH when? At strike? Ten minutes later? Twenty minutes later?' And another question is 'What temperature?'.

Test strips are notoriously bad for use in determining mash pH. Your low pH reading is typical. Quite a bit of work has been done on this and you can find references to it all over the internet. In particular check out Kai Troester's (Braukaiser) stuff. One of the things I found while participating on one of Kai's experiments was that it was difficult to compare test strip colors to package legend colors because the test strip colors lay off the curve in color space that connected the legend colors.

pH meters can be a bit of a pain to use and maintain but if you want to really improve your brewing one is, like it or not, in your future. The good news is that they are much less expensive and more robust than they were even a few (10?) years ago.

EZ Water and ColorpHast strips can only get you in the ballpark. For my last several batches, I've used a Hanna pH meter, ColorpHast strips, and EZ Water. The strips have read 0.4 to 0.6 low,* and EZ Water has predicted 0.0 to 0.3 low. A pH meter is needed if you want any accuracy.

* The strip errors (for 6 batches) were: 0.4, 0.6, 0.6, 0.4, 0.4, 0.5. My conclusion: the strips are useless because they read extremely low, plus the error isn't consistent. Others have found more like 0.3 error.

SpeedYellow said:

EZ Water and ColorpHast strips can only get you in the ballpark. For my last several batches, I've used a Hanna pH meter, ColorpHast strips, and EZ Water. The strips have read 0.4 to 0.6 low,* and EZ Water has predicted 0.0 to 0.3 low. A pH meter is needed if you want any accuracy.

* The strip errors (for 6 batches) were: 0.4, 0.6, 0.6, 0.4, 0.4, 0.5. My conclusion: the strips are useless because they read extremely low, plus the error isn't consistent. Others have found more like 0.3 error.

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Brewkaiser's wiki page states you a mash of 5-6 is acceptable, with 5.3-5.5 being optimal. That to me says that strips are going to be "good enough" for most brewers. Sometimes "ballpark" is good enough...

Thing is that there is a vast difference between acceptable and optimal (or let's be real, near optimal) beer.

Thanks for the feedback everyone, it looks like I will be buying a pH meter sooner than later. Any good links to threads that discuss a simple and easy to use meter?

From the under $100 'pen' types to the $200 one that uses my iPhone as the electronics to the over $1000 lab bench top instruments that can be controlled by your computer basic use is all pretty much the same. The material at https://www.homebrewtalk.com/f128/ph-meter-calibration-302256/ will give you a general idea as to what is involved.

ajdelange said:

Thing is that there is a vast difference between acceptable and optimal (or let's be real, near optimal) beer.

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True, but that isn't what we are talking about....do you think you can taste the difference between a beer mashed at acceptable pH versus optimal mash pH?

Oh yes. Definitely. I often describe the difference as the difference between a beer that makes you say "OK" and one that makes you say "Ah". Another guy who got the religion said proper pH made all the flavors in his beers brighter.

Are those sub $10 pen type ph meters from ebay/china any good? The yellow candy bar type ones that are proliferate at that price point. They seem ok online and review up ok but nobody talks about the longevity of them. I've got a couple of types of pH strip on order, narrow band 3.5-5.5 and 5.5-7.5 or something similar from memory and figured they'd get me 'ballpark' from tap water, to mash pH ranges but now I'm considering a meter. I'd likely forget it though if the barrier to entry (cost) is significant for the right tools.

No. 'The bitterness of poor quality remains long after the sweetness of low price is forgotten'. The cheapies ($100) tend to suffer from instability. https://www.homebrewtalk.com/f128/ph-meter-calibration-302256/ suggests a test for stability which is easy enough to carry out. If the meter is somewhat unstable it can still be used by frequent calibration. This is not as bad as it sounds as once you have made up the buffers it's pretty quick and easy with a modern meter. If I had to guess I'd say $150 - $200 would be the minimum you can spend and get a really stable meter i.e. one you can calibrate in the morning and have it hold cal through the day. If you are willing to spend that much on the electrode alone you may find that it holds cal for days or even weeks (but you should recal it each day or at least check the cal each day you use it.).

+1 on AJ's comments that you'll have to spend to get quality and performance. However for my typical short duration usage, I have found that a more modestly priced meter and probe can do for short periods reliably. A MW-101 has proven acceptable for me. Someone in a brewery would likely want a better meter though.

On cheap meters: I bought a Hanna 98107 from Amazon for $40 ~2yrs ago and have brewed 20 batches using it. It needed to have the electrode seasoned in storage solution overnight to calibrate correctly. After that, it has worked flawlessly. It reads pretty close(within .1) of what EZ water predicts with RO and modest CACl2, CaSO4, acid malt, and phosphoric acid additions.

On brewday, it has never read more than .1 off when I'm calibrating it and 97% of the time has not even been off at all. I keep it stored in storage solution and rinse with D/I water in between readings, mix powdered capsule buffer solutions ~ every 3 months or so and it's been a really good cheap meter.

My beer is good, no astringency and I brew mostly light lagers. Recently one scored high 30s with 3 BJCP judges--only dinged for a little acetaldehyde thrown by some cantankerous WY2278 that crapped out at the end of fermentation.

I know my meter could be better(only reads to .1), but it's what I could afford at the time and it works great. Over the last 3 months or so it has taken a little more time to settle on its reading but when it settles, it stays there and doesn't drift. I have no regrets on buying this meter and would recommend it to anyone on a budget.

I was considering purchasing a meter a few years ago when I started doing all grain. After seeing the need do a two point calibration I decided that I didn't want to have to do one more thing on brew day. So I talked to the people at Micro Essential Labs and they suggested pHydrion Lo Ion test strips. You can find them on amazon for $12 (http://www.amazon.com/dp/B007VD6BMU/?tag=skimlinks_replacement-20). I can definately tell the difference between a mash pH at 5.0, 5.5 or 6.0. That is the increments with these papers. Also remember, you will record a different pH at 150 then at 70 F. I fill the sample tube with the mash liquid about 15 minutes after adding my brewing salts and drop in a bucket of tap water at 70. Allow to cool and then test.

It has been my experience that the EZ water spreadsheet estimates a pH of 0.1 to 0.3 higher than what I read from the strip but this is slight subjective because the 0.5 increments on the paper.

Best of luck,
BB

Low ionic strength is the reason that the ColorpHast manufacturer says that their plastic pH strips should be immersed for at least a minute in order to obtain a viable reading. Although wort is full of sugars and starches, its ionic strength is very low. These pHydrion strips might be OK for use since they seem to be geared for low ionic strength liquids. The 0.3 unit offset in reading seems consistent with the ColorpHast strips. The 0.5 unit reading precision isn't great, but its a lot better than nothing (if it's readings are otherwise consistent). I haven't used them, so I can't comment further. Thanks for the note.

mabrungard said:

Low ionic strength is the reason that the ColorpHast manufacturer says that their plastic pH strips should be immersed for at least a minute in order to obtain a viable reading.

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I'd be curious as to what they have to say about that. Have a link? Doesn't seem to me that ionic strength would have anything to do with it. Low ionic strength is a problem with electronic measurement as pure water is a pretty good insulator and a current, even though a very feeble one, must flow for an electronic meter to work. Even so there are workarounds: add an ion strength enhancer (ISE) and calibrate with buffers that work properly with that ISE.

mabrungard said:

Although wort is full of sugars and starches, its ionic strength is very low.

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Low relative to a saturated solution of zinc sulfate perhaps but not low relative to the ionic strength of nominal tap water which is usually enough to produce a pfm ~ 0.03 (think of this as a pH offset) or so. Remember that in addition to the minerals (ions) from the liquor that malt itself adds quite a few ions to the mash.

Here is an error summary from EM ColorpHast.

View attachment pH Error Sources.pdf

Personally I think it is worth getting a meter that allows you to check the slope and MV offset. Slope should be >90 and of set should be no more than +/-10. These features give you a good idea of the "health" of your probe.

Not sure if these cheap ones do that but I'll be in the market for a personal meter soon.

mabrungard said:

Here is an error summary from EM ColorpHast.

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Thanks. I see what they are on about. The dyes are weak acid/base pairs with particular pK values and the color depends on the ratio of protonated to unprotonated forms. This is, as with any other pair r = 10^(pH - pK + pfm) with pfm having a value around 0.02 or so for nominal tap water and probably about the same with wort. For strips with a precision of 0.3 pH I don't expect that will be a problem. Note that I said you can think of pfm (which is a function of ionic strength) as a pH shift but as the ratio formula clearly shows you can think of it as a pK shift if you prefer.

The acid/base nature of these dyes is illustrated nicely in the picture (3rd graph) at http://www.wetnewf.org/pdfs/measuring-alkalinity.html where you can clearly see the pH reducing effect of adding bromcresol green-methyl red to a water sample whose alkalinity is being measured. I guess the message from this is add as little indicator as you can - just enough to let you see the color.

Dolomieu said:

Personally I think it is worth getting a meter that allows you to check the slope and MV offset.

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You can, of course, do that with any meter that has a millivolt mode but what is nicer than that are the meters that display slope and offset automatically as a part of the calibration process and, better still, log this info.

Dolomieu said:

Slope should be >90 and of set should be no more than +/-10.

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I've noted that most meters that do this won't allow cal to take place if slope is less than 95%. To my cynical mind it occurs that setting the threshold this high allows the manufacturers to sell more replacement electrodes than if they set it for 90% or 85% and that brings up the question as to how high it really needs to be. Clearly your measurement 'signal to noise ratio' goes down as the slope goes down but not appreciably at even the 80% level so why not use the meter at much lower slopes than 95% (given that you put it in mV mode and do the calculations yourself).

Dolomieu said:

These features give you a good idea of the "health" of your probe.

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I recommend that people keep a log and enter this data each time they cal. That way one can observe the aging pattern of the electrode.

Dolomieu said:

Not sure if these cheap ones do that but I'll be in the market for a personal meter soon.

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No, I don't think they do.