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Old 08-15-2013, 07:43 AM   #1
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Default Using Ph Meter for first time.

So after much reading in this forum the common denominator seemed to be "use a ph meter" rather than guessing. So I ordered one for my next batch. I ordered the MW102 and just have some questions about using it. I haven't been able to find a definite answer, and could use some clarification.

According to the Brun Water my mash ph is supposed to come out to 5.3. I have 11.5 lbs 2-row, 2 lbs munich, 1lb crystal 20, 8oz carapils, and 8 oz acid malt added in the spreadsheet. So after I mash in should I take a reading right away or should I wait 5 to 10 minutes. I have read conflicting answers on the forum. I know from reading that the PH will continue to climb a little during the beginning of the mash. After how long will it stabilize?
After I mash in and the ph appears to be too low or even possibly too high(shouldn't happen with this grist) is there anything I can add in time to raise/lower the PH to within the acceptable range? Or do I just have to make some adjustments for the next brew?


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Old 08-15-2013, 12:45 PM   #2
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For a NFBL member, from a former NFBL member.

The vigor and completeness of the mash or wort mixing has a direct effect on the speed at which the mash pH stabilizes. In addition, acid malt use probably does slow the delivery of acid into the mash. So a little extra time may be needed.

I use liquid acids and run a RIMS, so the mixing and reaction is fairly rapid. I typically collect a sample at around 5 minutes after dough in. The reading is fairly stable and I see about a tenth of a unit rise during the mash. Others have reported a slight fall in pH during the course of the mash. Possibly the use of acid malt could have an effect on that falling pH phenomena.

In my opinion, chasing a 'perfect' mash pH is foolish without guidance. Since mash pH response is relatively linear with respect to mash acidity, there is less of the 'cliff' effect that you can get when acidifying water. That is the case where you add drop after drop of acid and only get minor reduction in pH. Then all of a sudden the pH plummets with another drop of acid (the water's alkalinity was exhausted). So anyhow, use Bru'n Water and play with targeting a mash pH a tenth higher and lower and see how much difference is incurred with either extra acid or base needed to effect that change. That will give you an idea of how much of those substances you might want to add if the pH is really off that much.

However with that said, I recommend that if the pH is only a tenth or two off, live with it for this batch. Don't chase your tail trying to get the pH right with extra acid or base additions. Live and learn, jot that note down that the pH was high or low and make adjustments to your target.


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Old 08-15-2013, 01:14 PM   #3
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What happens with pH over time depends on the nature of the mash. It takes some time for whatever is reacting to react. If you have a mash to which you have added acid (in the form of liquid, powder or dark grains) some of that will be quickly released into the liquid and the pH will plummet and then rise over time as the liquid is absorbed by the grains and the acid reacts. If you add base the opposite will occur.

Agitation, of course, has a lot to do with this. There is a chart at http://wetnewf.org/pdfs/estimating-mash-ph.html which represents a recording of pH over time in a test mash made by adding finely ground to a mixture of acid and water. You can see both the pH creep and the effects of stirring on the pH from that recording.

My experience in the brew house has been that where sauermalz is involved with minimal calcium the pH rises throughout the brew day having more or less stabilized after 15 - 20 minutes in the mash. My experience with more mineralized water has been that the pH stabilizes after about 20 minutes after dough in but then drops slightly after each decoction.

If you try to chase pH in the mash tun do it with liquid acid - not by stirring in powders, especially chalk. Powders are hard to mix, expecially if you have a thick mash, and the danger is that you will measure pH in a portion of the mash which the powder didn't reach or where the powder hasn't dissolved. If you want to use lime or baking soda dissolve them in a pint of water first and then add that pint in increments so as to no overshoot.

Better than trying to fix the pH in the mash is to know what it will be in advance. You can determine this by making a mini mash of about a pound of your grist (make sure it is well mixed) with a quart or so of the water (warmed to the proper temperature). Adjust the grist or the acids/bases added to the liquor, until the pH is where you want it to be. Then scale to the full brew. You ought to be able to hit the desired pH to within Ī 0.05 units this way. Don't worry about being off by that much. Keep good records and use a bit more or less acid next time to try to 0 in. Variations between lots of malt will swing you about a bit but with experience you will be pretty close to what you want at each brew.

Starting off with a pH meter presents some frustrations. As with any new piece of equipment there is a learning curve. I suggest that people ascend that curve as far as possible before brew day. There are some comments on the proper use and calibration of pH meters at http://www.homebrewtalk.com/f128/ph-...ration-302256/ and even more details on what the meter does when you calibrate it at http://wetnewf.org/pdfs/ph-meter-calibration.html. The instructions that come with the meter should be followed if they conflict with the instructions at the link I just gave.

Calibrate your new meter and go about the house (kitchen mostly) measuring the pH of orange juice, vinegar, milk, baking soda solution, household bleach, beer etc. You should be able to find generally applicable pH values for these on the web. Then turn to measuring the pH of bits of crushed malt in water.

Sometimes your pH meter will give you a surprising answer and the art of using one lies in being able to detect a suspicious reading. If you get an unexpected reading immediately rinse the electrode with DI water and immerse it in pH 4 buffer. If you don't read 4 (or close to it) recalibrate. Many a brewer has 'corrected' a calibration error in his meter by acidifying or alkalizing a mash.

Don't let me scare you with this. A pH meter is an invaluable tool once you learn to use it.
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Old 08-15-2013, 05:24 PM   #4
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I have been going through Bru'n Water like crazy just messing with different grists and seeing how it changes the ph. I had never thought about making a mini mash that is a great idea since normally I do 10 gallon batches it should be easy to scale..

When using liquid acid in the mash I have lactic acid on hand. I have seen some use phosphoric acid. Is there much of a difference to the two when using in the mash?
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Old 08-15-2013, 06:22 PM   #5
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The big difference is that lactate has a definite strong flavor all of its own. It is what gives sauerkraut, sourdough bread, witbier, yoghurt... their flavor. In the right place (witbier) it is delicious. In the wrong place it can ruin your beer (or at least make in less than conforming to the style you intended). Phosphoric acid, conversely, has an anion which is not very strongly flavored. It is used in carbonated beverages like Coke and Pepsi to impart sourness to balance all the sweetness of the tons of sugar. There is a whole lot of it in those drinks because there is so much sugar but those drinks (which used to be referred to a 'phosphates' for obvious reasons) don't have a flavor associated with phosphoric acid other than the sweetness balancing 'tang'.

As far as use in brewing is concerned many (such as the German government) feel that naturally produced lactic acid (from fermentation of wort by Lactobillius species) is preferable to phosphoric acid (produced by burning phosphorous and dissolving the oxide in water). Other than that there are some nuances with respect to the ability of the two to donate protons but these don't have practical effects on brewers (that I can think of at the moment anyway). So use either unless the lactate flavor is bothering you in which case reduce alkalinity or use the phosphoric.
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Old 08-17-2013, 04:36 PM   #6
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I am mashing right now and I took 3 PH readings. One at 5 min, one at 15 min, and 25 min into the mash. It seems kinda odd but my 5 min mash was 5.11, my 15 min was 5.11 and my 25 min was 5.13. I thought the PH was supposed to climb a little during the mash. The ph is calibrated using the buffer solution. I guess its not too bad because its within the acceptable range..

EDIT: I took a PH reading during my batch sparge and it read 5.11. Let me know if you see any issues with my numbers. So I can adjust for next time.
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Old 08-17-2013, 05:50 PM   #7
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Quote:
Originally Posted by tally350z View Post
I am mashing right now and I took 3 PH readings. One at 5 min, one at 15 min, and 25 min into the mash. It seems kinda odd but my 5 min mash was 5.11, my 15 min was 5.11 and my 25 min was 5.13. I thought the PH was supposed to climb a little during the mash.
It usually does but that doesn't mean is has to.

Quote:
Originally Posted by tally350z View Post
The ph is calibrated using the buffer solution.
Buffer? Don't you mean 'buffers'?


Quote:
Originally Posted by tally350z View Post
I guess its not too bad because its within the acceptable range..
You would like it a bit higher. Next time use less acid or more alkali.


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Originally Posted by tally350z View Post
EDIT: I took a PH reading during my batch sparge and it read 5.11. Let me know if you see any issues with my numbers. So I can adjust for next time.
This is a bit suspicious (i.e. having 4 readings within 0.02 pH). Did you do a check in one of the buffers?
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Old 08-17-2013, 06:30 PM   #8
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When I received the PH meter I calibrated using both the 4.01 and 7.01 buffers. I washed the ph meter with Distilled water before and after each reading, and I made sure the sample was a close to room temp as I could get it..

For my sparge water I used 50/50 RO and tap water. Used .8tsp of lactic acid along with some mineral additions.
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Old 08-17-2013, 11:57 PM   #9
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Quote:
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When I received the PH meter I calibrated using both the 4.01 and 7.01 buffers. I washed the ph meter with Distilled water before and after each reading, and I made sure the sample was a close to room temp as I could get it..
That isn't enough. You must calibrate the meter each day you use it at minimum and you must, until you have convinced yourself that it is stable, check on the calibration following the procedure at http://www.homebrewtalk.com/f128/ph-...ration-302256/ I am not declaring that failure to do this is responsible for the strange reading but it could be and needs to be checked out.
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Old 08-18-2013, 01:33 AM   #10
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Originally Posted by ajdelange View Post
That isn't enough. You must calibrate the meter each day you use it at minimum and you must, until you have convinced yourself that it is stable, check on the calibration following the procedure at http://www.homebrewtalk.com/f128/ph-...ration-302256/ I am not declaring that failure to do this is responsible for the strange reading but it could be and needs to be checked out.
It arrived yesterday which is when I calibrated it. Didn't know I needed to calibrate it today even after a day..


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