1st Time Using PH Meter

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wsmith1625

wsmith1625

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I bought a KegLand pH meter and decided to test it out before my brew day this weekend. It's my first pH meter, so I needed to figure it out. I have the storage solution and pH 4.0, 6.86, and 9.18 buffer packets. I mixed up 2 buffer solutions (4.0 & 6.86) each in 250ml of distilled water. Then I calibrated in both buffers. After doing that, it was accurately reading the buffer pH for both solutions. Then I tested the pH of the last beer I brewed which I suspected was slightly acidic. The measured pH was 3.96 which seems right to me. Then I measured a Sierra Pale Ale and it read the pH to be at 4.35. again that seems pretty accurate to me. Finally I went back and measured the pH of the distilled water I used to make my buffers. The measured pH was 5.2 which I was not expecting. I thought it would be neutral at 7.0. Are all my readings off because of this? Anyone else using distilled water for their buffers? I know it said to use deionized water, but that stuff is pretty expensive.
 
CO2 from the air dissolves into distilled water to form Carbonic Acid (H2CO3). But Carbonic Acid isn't stable and it readily dissociates back into CO2 and Water. ~5.8 pH is generally about where good distilled or deionized water exposed to airborne CO2 winds up stabilizing. That said, there are so few acid ions extant that the meter struggles to come to a valid pH reading for the case of distilled water. The motive force required whereby to gain a precise pH reading simply isn't there.

Short version: Distilled water is a terrible medium for determining the functionality of a pH meter.
 
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wsmith1625 said:
Did that. Rinsed it with distilled water then filled the cap with storage solution. Thanks.
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Good, you'll probably find that when you next look at the meter there will be crystals all over the cap where some storage medium escapes, don't worry about that. Unsure re kegland meter but I put a small piece of sponge in the bottom of the lid to hold the storage medium.
 
wsmith1625 said:
Anyone else using distilled water for their buffers?
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Yup, I do. Distilled water is fine for making buffers solutions. Labs use bi-distilled water, distilled twice.

BTW, those dry buffer pillows are way cheaper than the premixed solutions. And the pillows if you buy a bunch of them keep better too. ;)
Now expiration dates on mixed buffer solutions can be a mixed bag. I have 4.0 and 7.0 professional solutions 5+ years past their "exp. date," staying within 0.02, which is fine for brewing, in my book.
 
IslandLizard said:
Yup, I do. Distilled water is fine for making buffers solutions. Labs use bi-distilled water, distilled twice.

BTW, those dry buffer pillows are way cheaper than the premixed solutions. And the pillows if you buy a bunch of them keep better too. ;)
Now expiration dates on mixed buffer solutions can be a mixed bag. I have 4.0 and 7.0 professional solutions 5+ years past their "exp. date," staying within 0.02, which is fine for brewing, in my book.
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I bought a 30 pack of the dry buffer pillows for $12.99 which is a good price. I don't brew frequently enough for the pre mixed buffers to be cost effective.
 
wsmith1625 said:
I mixed up 2 buffer solutions (4.0 & 6.86) each in 250ml of distilled water.
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Maybe a question to the group. I have the same meter (well with the "Dr. Meter" brand, but it uses the same replacement probe as the KegLand one). The instructions say to calibrate with all 3 solutions, so that is what I do. I am not sure how important that step is. I work from the 9, to 7, to 4 solutions.

Somedays I am very happy with the accuracy of the meter, somedays I question it. It seems more reliable if I calibrate it on every brew day. I don't have experience with any other meters. Often when measuring my mash sample, it will "settle" at a value like 5.40 after 30 seconds, but then will continue to climb a hundredth every 10 seconds or so...5.41, 5.42, 5.43....5.56. I am never quite sure which value to trust, but at least I am pretty sure my mash is getting into a decent range.

After about 2 years the readings I was getting seemed a bit off. Replacing the probe helped with that. At another time I was getting odd readings, and then shortly after that the low battery indicator light up. Replacing the batteries got it back on track.
 
CascadesBrewer said:
The instructions say to calibrate with all 3 solutions, so that is what I do. I am not sure how important that step is. I work from the 9, to 7, to 4 solutions.
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Unless you'll be measuring pH above 7 (pretty unusual in brewing), you can skip the 9 (or 10 or whatever) buffer. It's not making your sub-7 pH measurements more accurate. BTW, always start with the 7, regardless of whether you are doing a 2 point or 3 point calibration. (You want to set the "zero point" first, before setting the slope with the second point.) The way you were doing it didn't hurt anything, because you were doing 7 before 4 (the relevant "slope" point for wort).

CascadesBrewer said:
Somedays I am very happy with the accuracy of the meter, somedays I question it. It seems more reliable if I calibrate it on every brew day. I don't have experience with any other meters. Often when measuring my mash sample, it will "settle" at a value like 5.40 after 30 seconds, but then will continue to climb a hundredth every 10 seconds or so...5.41, 5.42, 5.43....5.56. I am never quite sure which value to trust, but at least I am pretty sure my mash is getting into a decent range.
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Sounds like "drift," which can be caused by the probe and solution temperatures continuing to move toward equilibrium or by a less than stellar meter. Assuming your probe and wort are at about the same temperature, my guess is that it may be time to retire Dr. Meter, and invest in something more reliable.
 
Stirring inherently induces a 'false low' pH reading. Settling without stirring while the pH rises out of it's false low and until a stable reading is achieved is advised. Note that pH meters "stability indicators" generally seem to flash the "stable" sign way before they should. Perhaps that is by design, because patience is something that likely all of us lack.

Of course, as indicated by VikeMan it could indeed be a drift problem.
 
VikeMan said:
it may be time to retire Dr. Meter, and invest in something more reliable.
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The more likely option is to figure that I understand enough about how software predicts my pH that I can just skip measuring and rely on software predictions.

One strike against that plan is that when I recently moved from using 10% phosphoric acid to using 88% lactic acid I started reading a lower mash pH than the software* was predicting. It has been close enough that I don't adjust adjust during the mash, but taking pH readings has been helpful with planning future batches. Taking pH readings has also helped me get the mash for a Porter recipe into a better range.

Maybe I should find a local friend with a decent pH meter that I can try.

I do just let the meter sit still in the wort sample (taken at 30 minutes and chilled to 25C). The meter does not drift like that when measuring the calibration solution. It will settle on a value in 30 seconds and stay steady.

*for the record, I started off using Bru'n Water with good results (because it predicted mash pH better than BeerSmith), I played around a little with Mash Made Easy and some other sheets, then I found that the MPH model in the updated BeerSmith was working well for me when I was using 10% Phosphoric Acid. It was nice to not have to jump to another calculator tool. The couple readings I have taken adjusting with 88% Lactic Acid have come between the MPH and BW models in BeerSmith. It could be a measurement error on my end between ~30 ml of Phosphoric and ~2.5 ml Lactic.
 
If you are looking for a nominal equivalence with respect to a targeted pH of 5.4, then 2.86 mL of 88% Lactic Acid evolves the mEq equivalent H+ of 30 mL of 10% Phosphoric Acid. 2.5 mL of 88% Lactic Acid falls a bit short of the 'equivalence' mark.
 
Silver_Is_Money said:
If you are looking for a nominal equivalence with respect to a targeted pH of 5.4, then 2.86 mL of 88% Lactic Acid evolves the mEq equivalent H+ of 30 mL of 10% Phosphoric Acid. 2.5 mL of 88% Lactic Acid falls a bit short of the 'equivalence' mark.
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More just saying that when I need to use 30 ml of Phosphoric, if I am off by 1 ml, that is only 3%. If I am off 0.25 ml when my target is 2.5 ml of Lactic, I am off 10%. I might just need to make sure I am measuring accurately.

But.. @wsmith1625: Good luck with your pH meter and moving more into water chemistry. From what I can tell, that meter is one of the better cheap meters (better than the $10 ones, not up to the $130 ones, maybe not up to the level of the Apera meters in the $80 range). The fact that you can replace the probe for $19 is fairly unique with inexpensive meters.

At a minimum, for me it was a good introduction into the use, storage and care of a pH meter. Even if I don't trust the readings down to 0.1, I have a better understanding where my unadjusted batches used to be (with my water, a light grain bill would be around 6.0, ambers would be around 5.4, and I only need to raise the pH if above about 15% roasted malts). I do feel that adjusting pH has made a noticeable difference in the quality of my beers.
 
Also, be sure to give the intro post on this a read.
https://www.homebrewtalk.com/threads/ph-meter-calibration.302256/
I recall one issue I had before I replaced my probe. When I pressed the calibration button for the #4 solution, it would not cycle through the calibration steps. As I recall, it would calibrate with the other solutions.
 
CascadesBrewer said:
Also, be sure to give the intro post on this a read.
https://www.homebrewtalk.com/threads/ph-meter-calibration.302256/
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Looks good, thanks for sharing.

I knew when buying my pH meter that I didn't want to go too cheap but didn't want to spend the money on top of the line either. I had ordered a Milwaukee pH55 Pro, but had issues with the order and cancelled. Hopefully the Beverage Doctor will serve me well.

Water chemistry and pH has been a bit challenging to get a handle on, but I'm getting a lot of really good feedback from everyone to help me through it. Thanks.
 
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Brian66 said:
I have been looking for a PH meter under $100.
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Milwaukee MW101 can sometimes be found for under $100, but is usually a hair over.

I own an MW101 and an MW102 and would recommend either one.
 
VikeMan said:
Milwaukee MW101 can sometimes be found for under $100, but is usually a hair over.

I own an MW101 and an MW102 and would recommend either one.
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So are these that much better than the Apera AI311? The MW101 is $109 (no thermometer) and the MW102 is $126 - $30 and $50 more than Apera?
 

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