Mash pH too high

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Full Mental Jakey
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Mash pH too high

Post by Full Mental Jakey » Tue Mar 18, 2014 8:55 pm

Hi all, I'm looking for a little help. I'm clearly doing something wrong with my water treatment or use of Bru'n Water (which is a great spreadsheet, many thanks Martin). I'm aiming for a mash pH of 5.3, but getting 5.6. This has been the case for the last two brews, which is as long as I've had my pH meter.

Firstly, I'm measuring using a new pH meter (Extech pH220 - http://www.airconcern.co.uk/extech-ph22 ... p-645.html), which I calibrate to 4 and 7 before using. All samples are cooled to ~20 degrees before taking a reading, and I wait 10 minutes before taking the 1st mash reading. I'm also measuring alkalinity and calcium levels of my source water before brewing, but the water is very soft and the readings are close to the base accuracy of the kits. Here's what I had for my last brew...

pH : 7.9
Calcium : 20ppm (from test kit, which has a margin of error of the same magnitude, so take with a pinch of salt)
Magnesium : unknown
Sulfate : 17ppm (from water report)
Chloride : 4.8ppm (from water report)
Sodium : 4ppm (from water report)
Nitrate : 0ppm (from water report)
Nitrate : 0ppm (from water report)
Potassium : unknown
Iron : 0ppm (from water report)
Fluride : 0.2ppm (from water report)
Bicarbonate : 26ppm (from test kit)

My water treatment in the last brew was 0.1g/litre of gypsum, and 0.14g/litre of CaCl2, to boost my calcium up to 81ppm and have balanced sulphate vs chloride. These were added to the mash, along with 0.1mL/L of 75% phosphoric acid.

The grain bill was all pale base malt (half pilsner malt, half wheat malt, both from Dingemanns). In my previous brew, which had similar results, it was Fawcett's Maris Otter with a touch of light crystal.

Bru'n Water estimated a mash pH of 5.3, and all my readings were between 5.6 and 5.7.

What am I overlooking? My measured pH is barely lower than what Bru'n Water predicts it would be if I didn't treat the water at all. It could be that my phosphoric acid isn't exactly 75%, but even if I didn't add any at all, the pH should still be 5.5.

I'll be brewing again in the next few days, so if anyone can suggests some tests to do or things to try, it would be much appreciated. 5.6 is still in the ok range, but I'm curious to know why my numbers aren't adding up.

Dave S
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Re: Mash pH too high

Post by Dave S » Wed Mar 19, 2014 10:04 am

Are you treating the water with the phosphoric acid prior to heating? and adding the salts to the grist prior to mash in? From your post it sounds like you are mixing everything together in the mash. The alkalinity must be adjusted before heating the mash water. Mind you, from your water analysis it sounds like your alkalinity is already low. Do you need to add acid at all?

EDIT: Looking at you carbonate value of 26, you probably should be raising it rather than lowering it.
Best wishes

Dave

Mr. Dripping

Re: Mash pH too high

Post by Mr. Dripping » Wed Mar 19, 2014 10:12 am

You don't mention your alkalinty.....are you assuming this is the same as your bicarbonate of 26ppm??
If so, I would say that you do not need to add any acid to hit the desired mash pH range when making a pale beer.

At what temperature did you take your mash pH reading? You should cool the sample to 20 degrees. At mash temperature the reading is generally 0.3 points higher.

Dave S
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Re: Mash pH too high

Post by Dave S » Wed Mar 19, 2014 11:41 am

Mr. Dripping wrote:You don't mention your alkalinty.....are you assuming this is the same as your bicarbonate of 26ppm??
If so, I would say that you do not need to add any acid to hit the desired mash pH range when making a pale beer.

At what temperature did you take your mash pH reading? You should cool the sample to 20 degrees. At mash temperature the reading is generally 0.3 points higher.
Isn't it meant to be 0.3 points lower at mash temp? and apparently that's debatable too.
Best wishes

Dave

barney

Re: Mash pH too high

Post by barney » Wed Mar 19, 2014 11:52 am

How soon after mashing are you taking the reading? you must let the mash proceed for 15-20 minutes, before then the mash may not have reached its final acidity level. Let the sample cool to room temperature, as near to 20C as possible.

What is the grist/ liquor ratio?

What is the ABV? A mash acidity of 5.6 can be really helpful in generating that bit of extra body at low alcohol levels, when used in conjunction with mash temperature.

There is no need to acidfy the mash with phosphoric acid.

Full Mental Jakey
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Re: Mash pH too high

Post by Full Mental Jakey » Wed Mar 19, 2014 12:20 pm

Thanks for the reply guys. I'm measuring the alkalinity directly using a salifert kit. That is coming out at 1.2dKH, which I believe is 26ppm bicarbonate (using the Bru'n Water calculator).

Like yourselves I was expecting not to have to do any acidification. My measured pH isn't far off what is reported for distilled water mashes (and my water isn't far off, being so soft), which suggests that my additions are doing nothing (which I can't believe).

The 0.3 difference between room temperature and mash temperature pH was something that I thought might explain my results (if I'm measuring 5.6 at room temperature then mash temperature pH is spot on at 5.3). But everything I read suggests that all measurements and suggested ranges are at room temperature (as are my measurements).

I did add all treatments to the mash for my last brew. I'll add the salts to the mash next time, and the acid to the strike water, but I can't help but feel something else is going on. Even with unadjusted alkalinity I'd expect the pH to be lower. Maybe I should approach this a different way - for an all pale-malt grist, what is the ideal alkalinity of strike water? I can target that and measure that I'm in the right ball-park...

Full Mental Jakey
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Re: Mash pH too high

Post by Full Mental Jakey » Wed Mar 19, 2014 12:23 pm

barney wrote:How soon after mashing are you taking the reading? you must let the mash proceed for 15-20 minutes, before then the mash may not have reached its final acidity level. Let the sample cool to room temperature, as near to 20C as possible.

What is the grist/ liquor ratio?

What is the ABV? A mash acidity of 5.6 can be really helpful in generating that bit of extra body at low alcohol levels, when used in conjunction with mash temperature.

There is no need to acidfy the mash with phosphoric acid.
Hi Barney, I waited 10 mins before my 1st measurement this time (20 mins for my previous brew), but I've been measuring a couple of times over the course of the mash, and at mash-out, and I don't note a significant drop over that time.

One thing I forgot to mention is that I use HERMs and the wort is continually being recirculated. I'm not sure if this makes a difference in any way.

Grist/liquor ratio is 3.0

Both brews have been in the "normal" ABV range of 4.5-5% .

Dave S
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Re: Mash pH too high

Post by Dave S » Wed Mar 19, 2014 12:47 pm

Full Mental Jakey wrote:Thanks for the reply guys. I'm measuring the alkalinity directly using a salifert kit. That is coming out at 1.2dKH, which I believe is 26ppm bicarbonate (using the Bru'n Water calculator).

Like yourselves I was expecting not to have to do any acidification. My measured pH isn't far off what is reported for distilled water mashes (and my water isn't far off, being so soft), which suggests that my additions are doing nothing (which I can't believe).

The 0.3 difference between room temperature and mash temperature pH was something that I thought might explain my results (if I'm measuring 5.6 at room temperature then mash temperature pH is spot on at 5.3). But everything I read suggests that all measurements and suggested ranges are at room temperature (as are my measurements).

I did add all treatments to the mash for my last brew. I'll add the salts to the mash next time, and the acid to the strike water, but I can't help but feel something else is going on. Even with unadjusted alkalinity I'd expect the pH to be lower. Maybe I should approach this a different way - for an all pale-malt grist, what is the ideal alkalinity of strike water? I can target that and measure that I'm in the right ball-park...
With an alkalinity of 26 you definitely don't need to lower it further with acid. In fact I'd say you probably need to increase it to the 30-50 range. I always try to aim for about 40 for a pale ale profile. As for the high pH, it shouldn't be so if you are mixing the correct amounts of calcium sulphate/chloride to the grist, then mashing in.
Best wishes

Dave

WallyBrew
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Re: Mash pH too high

Post by WallyBrew » Wed Mar 19, 2014 12:56 pm

Have a read of this and see whether 5.3 is where you want to be.

Be aware it is a direct link that will download. It is also on the reading list for one of their examinable courses

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mabrungard
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Re: Mash pH too high

Post by mabrungard » Wed Mar 19, 2014 2:20 pm

If you are confident in the alkalinity/bicarbonate value from the test kit, you could perform a quick evaluation of your acid strength using the acidification calculator. Plug in your resulting test kit alkalinity into the calculator and then figure out how much 75% phosphoric you would need to add to a liter of water to bring the alkalinity to zero. After that treatment, test the treated water to see if it does have zero alkalinity.

Another potential source of pH anomaly is the calcium chloride. I understand that it can sometimes have a trace of lime. Add a little to your tap water and measure the pre- and post-addition water pH to see if that is a problem.
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