Sudden problems predicting mash pH

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chrisr
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Sudden problems predicting mash pH

Post by chrisr » Thu Jan 03, 2019 8:44 pm

I’ve been having a bit of trouble hitting the optimum mash pH consistently lately and would appreciate any advice or ideas.

I’ve been brewing for years, once I’d started with water treatment I used John Palmer’s water calculator, but about 9-12 months ago I changed to Bru’n Water. When I first started using Bru'n Water, I was astounded at how accurate its predictions were. It was usually predicting within pH0.05 of what actually happened in the mash. I think I did somewhere around 10 brews where it was effectively spot-on with the pH prediction. It was a joy to use.

Suddenly, it's not predicting accurately any more - or something is going wrong in the mash. The actual outcome can be up to pH0.5 higher than the prediction, which often sends the mash out of the optimum pH region. This issue has been apparent over my last four brews, which have been different grists, from an IPA to a stout.

I take the sample at 10 minutes in, and let it cool before testing with a pH meter. I usually recalibrate, with two references, before starting the brew.

My brewing kit is unchanged, and I'm not aware that I'm doing anything process-wise differently to the way I have always worked. The ingredients changed slightly, due to different recipes, but everything came from the same stock, in particular the same bag of pale malt.

So I'm thinking the only thing that can have changed is my source water (mains supply) but I've checked the utilities web page for the water report and it's the same as usual. The mains water pH measures the same it always has. I’m in a soft water, low mineralisation area, so the water treatment is basically burtonisation.

Thanks for any advice or ideas you can offer...

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Re: Sudden problems predicting mash pH

Post by john luc » Fri Jan 04, 2019 12:56 am

best I can advise is that if everything is the same then it's your PH meter that's gone wonky. I know you say you check calibration but they are delicate yokes.
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Re: Sudden problems predicting mash pH

Post by FUBAR » Fri Jan 04, 2019 8:33 am

Local water reports are just an average for the area and can in theory be way off your actual water profile.It can't be recommended enough that you get in touch with Wallybrew on here for a water report,for a small fee you will get an accurate report of everything in your water that is necessary to brew successfully.Used in conjunction with a salifert kit everytime you brew to check the alkalinity would be the way to go.
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Re: Sudden problems predicting mash pH

Post by Aleman » Fri Jan 04, 2019 9:27 am

pH Meter failure, or more probably your water has changed composition. The most critical piece of information is alkalinity, and that needs to be measured and used in place of any guestimate of alkalinity based on 'Hardness' or calcium Levels.

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Re: Sudden problems predicting mash pH

Post by Robwalkeragain » Fri Jan 04, 2019 10:20 am

Do you have a previous brew you have a recorded ph for? Can reference against that to see if your meter is nackered.

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Re: Sudden problems predicting mash pH

Post by PeeBee » Fri Jan 04, 2019 10:48 am

When things aren't going right never give the impression you don't know what's going on. Just blame the tools.

-------------------------

Okay, that's a bit of a scoffing response, but I've gone through all 2018 with the water calculators (and I use Bru'n Water too) failing to predict the mash pH. But I was erring the other way and haven't had a mash pH reading higher than 5.2 in all that time (usually 5.0).

Has it had a detrimental effect on my beer?

Has it heck!

Cured me of the pathetic chasing of the "ideal" mash pH though.

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Re: Sudden problems predicting mash pH

Post by chrisr » Fri Jan 04, 2019 4:50 pm

Thanks for all your thoughts.

I did suspect my pH meter first, as I've had it a while now. So I bought a new sensor. Same readings.

Everyone in my area gets their water from the same place, the Ladybower/Derwent dams complex. (That water is sent all the way down the valley as far as Derby and Nottingham) There are alternative sources further south, but I can't see them pumping it uphill all that way! I did have a water report from Murphys, a few years back, while not precisely what Severn Trent said, everything was in the same ball-park.

I've been wondering about the alkalinity, too, as that's supposedly the major influencer. I will get a test kit, and see if reality tallies with what Severn Trent claim.

We have had a very dry summer here, and the dams were as low as they were in 1976 (was it? - the drought summer). You may have seen the pics of the submerged Derwent village revealed, in the news. I did wonder if perhaps something has become more concentrated in the water. The water is basically just runoff from the moors. ST appear to update the water report every 3 months, so it could be 3 months out-of-date now.

I take the point on pH-chasing, but I would prefer to get it somewhere in the range considered optimum. There are times it's been so far out, the conversion has been affected, and I've been liters short of what I expected.

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Re: Sudden problems predicting mash pH

Post by Dave S » Fri Jan 04, 2019 5:07 pm

chrisr wrote:
Fri Jan 04, 2019 4:50 pm
Thanks for all your thoughts.

I did suspect my pH meter first, as I've had it a while now. So I bought a new sensor. Same readings.

Everyone in my area gets their water from the same place, the Ladybower/Derwent dams complex. (That water is sent all the way down the valley as far as Derby and Nottingham) There are alternative sources further south, but I can't see them pumping it uphill all that way! I did have a water report from Murphys, a few years back, while not precisely what Severn Trent said, everything was in the same ball-park.

I've been wondering about the alkalinity, too, as that's supposedly the major influencer. I will get a test kit, and see if reality tallies with what Severn Trent claim.

We have had a very dry summer here, and the dams were as low as they were in 1976 (was it? - the drought summer). You may have seen the pics of the submerged Derwent village revealed, in the news. I did wonder if perhaps something has become more concentrated in the water. The water is basically just runoff from the moors. ST appear to update the water report every 3 months, so it could be 3 months out-of-date now.

I take the point on pH-chasing, but I would prefer to get it somewhere in the range considered optimum. There are times it's been so far out, the conversion has been affected, and I've been liters short of what I expected.
As others have said, get a Salifert kit and a reliable analysis from Wallybrew. You might also consider a cheap TDS meter, (about £3). Test the sample you send to Wallybrew, then use that as a yard stick for subsequent brews. It will tell you if your water has changed significantly since it was tested. Of course your pH meter may still be at fault. What type is it and how old is the probe?
Best wishes

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Re: Sudden problems predicting mash pH

Post by chrisr » Fri Jan 04, 2019 6:04 pm

Are you saying I shouldn't put any faith the Murphys analysis? It did pretty much match what Severn Trent said.

The old probe is getting on a bit. But I have new one, less than a month old. That gives the same readings as the old probe (once calibrated).

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Re: Sudden problems predicting mash pH

Post by guypettigrew » Fri Jan 04, 2019 6:17 pm

What does your ST report say, and how do you treat the water?

Guy

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Re: Sudden problems predicting mash pH

Post by chrisr » Fri Jan 04, 2019 7:22 pm

See
https://www.stwater.co.uk/my-supply/wat ... r-quality/
and enter post code de45 1aa.

The Murphy's analysis adds:
Alkalinity 12mg/L CaCO3
Calcium 14mg/L
Sulfate 20mg/L
Chloride 14mg/L
I tend to believe them, as we have very soft water, very low mineralisation.

A campden tablet in the HLT prior to starting. Use Brun Water spreadsheet to determine the additions of CaSO4 and CaCl2 required to a/ ensure sufficent calcium and, b/ get the Cl2/SO4 balance right to match the beer style. For most brews there's nothing else required.

I put the salts in a measuring jug with a bit of warm water, and use the liquidiser on it. Tip this into the HLT (I treat all the water the same, in one go).

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Re: Sudden problems predicting mash pH

Post by Eric » Fri Jan 04, 2019 8:48 pm

Seven Trent's figures suggest their water doesn't vary by any amount to be concerned, but equiped with a cheap TDS meter and a Salifert kit would remove all your doubts and confirm your supplier isn't forced to provide you with an alternative supply.

Murphy's didn't have the best of reputations for water testing in the past, but they are in the majority of cases suitable for purpose. WallyBrew provides a more comprehensive report, checked in a way it would seem Murphy's either don't fully understand or care to apply. However in the figures you give it looks as if they got the amount of chloride correct and the difference between their findings and Seven Trent's are not of major significance or concern.

Your pH measurements would be improved if you were to take a later sample and cool the wort more quickly. Aleman has always advised using a shot glass or similar direct from the freezer for this purpose which I now always use, then quickly transfer the sample to a small plastic cup when the temperature reaches 20C. If your probe is old this could be the problem as its readings will drift despite being recently calibrated. Another problem is contamination of the probe, when not rinsed in running deionised water between measurements.

You say you have used the same bag of malt, but are your recipes identical for each brew? All grains vary by species, from field to field, maltster to maltster, batch to batch that I constantly wonder how so many brewers find pH prediction calculators to be worthwhile. This paper gives an insight into the degree of variation in the same and different types of barley malt and suggests more data should be supplied by maltsters so that brewers can compensate by varying the amount of calcium present in the brewing liquor, but maybe that was written before the advent of calculators for low mineral water brewing assuming ales should be brewed and taste like lagers.
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Re: Sudden problems predicting mash pH

Post by mabrungard » Sat Jan 05, 2019 3:57 am

Have you changed your mashing thickness? If you've moved to a thinner mash, that does affect mashing pH and I can report that current versions of Bru'n Water do not predict pH very well when the mash thickness is thinner than about 4 liter/kg. There is testing and recalibration currently being conducted to improve the program's prediction capability in thin mashes. Mashing in the 2 to 4 l/kg range should be fairly accurate.
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Re: Sudden problems predicting mash pH

Post by chrisr » Sat Jan 05, 2019 12:18 pm

I've ordered a Salifert alkalinity kit.

Eric, What does a TDS meter do for me, brewing-wise. I've just read up what it meaures, but how does that relate to brewing? (There's always something new to learn about brewing, isn't there?)

Do you mean take the sample later on in the mash? At what time? I know there are a lot of reactions under way in the first stages of the mash, and the pH will change. I thought 10 mins would see it settled.These 'problem' brews have been a different recipe every time; stouts to pale ales.

I mash around 2.5-3.0 l/kg.

I'm not trying to hit a precise pH, and I don't obsess about that, I just want it to fall into the optimum range, reliably.

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Re: Sudden problems predicting mash pH

Post by PeeBee » Sat Jan 05, 2019 2:54 pm

chrisr wrote:
Sat Jan 05, 2019 12:18 pm
I've ordered a Salifert alkalinity kit. ...
Should have chipped in a bit quicker...

The alkalinity kit might do you no use at all! Mine certainly didn't (also moorland - acid - water). I used to live near Derby so I know the water is soft from the Ladybower reservoir group. The alkalinity might show up as the lowest the kit can show (watch out - the sample might go pink after only one or two drops of reagent).

The water company might fiddle with the alkalinity so that the pH stays within a desired range. The drought could have resulted in more fiddling (my water went from pH 7.5 to pH 8.5). But the quantities of "adjustment" are miniscule in water that has very little in it (and therefore little buffering capacity). The adjustments are just to preserve the iron pipes (where they haven't been switched for plastic - that means most pipes are still iron).
chrisr wrote:
Sat Jan 05, 2019 12:18 pm
Eric, What does a TDS meter do for me, brewing-wise. I've just read up what it meaures, but how does that relate to brewing? (There's always something new to learn about brewing, isn't there?)

Do you mean take the sample later on in the mash? At what time? I know there are a lot of reactions under way in the first stages of the mash, and the pH will change. I thought 10 mins would see it settled.These 'problem' brews have been a different recipe every time; stouts to pale ales.

I mash around 2.5-3.0 l/kg.

I'm not trying to hit a precise pH, and I don't obsess about that, I just want it to fall into the optimum range, reliably.
TDS = "Total Dissolved Solids". Doesn't say much in itself but helps confirm results from other sources. And some of those "results" might well be your own assumptions filling in unreported stuff. Again, like "alkalinity", not so useful when the water doesn't contain much anyway (acid moorland water).

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