Brun Water vs mini-mash vs first runnings

[MikeInMKE]

Today I brewed a modified recipe of Can You Brew It's Moose Drool.

As I have done for the last half dozen brews, I brewed with RO water, entered all necessary data into the Bru'n Water spreadsheet, more or less adjusted the salts to the style chosen (I now ignore magnesium), and brewed. Bru'n Water predicted a mash pH of 5.3 - right where I wanted to be.

But today I used my brand new pH meter, a Milwaukee MW102, which BTW, calibrated really nicely. I could get very repeatable readings on both the buffers as well as the rinse solution, so my confidence in this instrument is high.

For the first time, I made a mini-mash. I used a very good scale that read to the hundredth of a gram to weigh out the ingredients. The pH of the mini-mash came in at 6.3, too far away to fix with sauermaltz, and would take a ****-ton of 10% phosphoric acid to fix, so I said fsck it, it's time to mash, good or bad.

I know far brewers far better than I who don't give a crap about their water, so I decided to mash in anyways, knowing I'd make beer, regardless. After draining the first runnings, I mixed well and snagged a small sample which turned out to have a pH of 5.38! Very close to Brun Water's prediction, and right about where I wanted to be.

So, I'm happy. Happy with Brun Water (thanks Martin!), happy with my new pH meter, happy I brewed beer today, but not so happy with my mini-mash being so far off.

 

[ajdelange]

Milwaukee MW102, which BTW, calibrated really nicely. I could get very repeatable readings on both the buffers as well as the rinse solution, so my confidence in this instrument is high.

For the first time, I made a mini-mash. I used a very good scale that read to the hundredth of a gram to weigh out the ingredients. The pH of the mini-mash came in at 6.3, too far away to fix with sauermaltz, and would take a ****-ton of 10% phosphoric acid to fix, so I said fsck it, it's time to mash, good or bad.

People just starting out with pH meters often have experiences like this and there is an explanation for each and everyone but I have no idea as to what the explanation may be in your case. There is, of course, no way you can mix malts with RO water and small quantities of neutral salts and come up with a pH as high as 6.3 so your meter reading was off for some reason. As you gain more experience with pH measurement you will find that somehow these way off readings tend to stop appearing or perhaps it is that you become sensitized to the fact that such readings are out of whack and try to run down the cause of them. If you see a reading this far out of whack the first thing to do is squirt DI water on the business end of the electrode and repeat the reading. Perhaps a piece of grain was blocking the junction. If this doesn't get you a good reading then rinse again and check the two buffers and do a stability check (see the Sticky on pH cal if you haven't already). It is only fair to warn you that the Milwaukee meters do not enjoy a good reputation and so you should be alert to the fact that you may get erratic readings from it. OTOH you may not - some people have better luck with these meters than others.

Nearly all the inexpensive meters suffer from instability to some extent - that's why they can be sold for the low prices they command. It is always a good idea to check the buffers after each reading when using them. If it turns out you are lucky and have a stable electrode then the post measurement check will always pass and you can stop doing them after every measurement. As I said earlier, with experience you will develop a sense of when a reading is off but we have all spent a brew session chasing the vagaries of a whacky pH meter at some point in our brewing careers.

 

[MikeInMKE]

People just starting out with pH meters often have experiences like this and there is an explanation for each and everyone but I have no idea as to what the explanation may be in your case.

Just a guess... I live just north of Milwaukee, I was brewing out in my garage, the garage door was open, and a storm was raging outside. For whatever reason, I chose to bring the instrument, the buffers, rinse water, and sample out into the garage to take the readings there. I'm guessing all that cold and wind might have caused the ATC to throw too much fudge factor into the calculation.

The next time, I will do it all indoors in a temperature-stable environment.

If you see a reading this far out of whack the first thing to do is squirt DI water on the business end of the electrode and repeat the reading. Perhaps a piece of grain was blocking the junction. If this doesn't get you a good reading then rinse again and check the two buffers and do a stability check (see the Sticky on pH cal if you haven't already).

I had read the sticky, and had kept shot glasses of the buffer solutions so I could verify the instrument's calibration before and after taking any readings of the mash. The instrument always correctly read the pH of the buffer solutions.

When I measured the pH of the first runnings, it was hours later after the brew was done and everything was cleaned up and put away. The sample had been sitting in a shot glass on my kitchen counter, next to the meter and buffers. No cold wind.

 

[ajdelange]

It wouldn't be ATC. At ph 5 the correction between temperatures of 20 °C and 50° C calculated by ATC would be (7-5)*( (273 + 50)/(273 + 20) -1 ) or about 0.2 pH

 

[mchrispen]

I have the non-ATC version of that meter (MW100) - and love it. I have noticed that the meter probe needs to "warm up" a bit, so I use a power cycle process that includes a few minutes of power-on while in storage solution, then a calibration step. I leave the meter on through the first 20 minutes or so of mash in to avoid cycling the power. Then I rinse the probe, replace the storage solution and set it aside. I have also noticed that if the power meter shows just 1 bar of battery power - then the readings are less reliable.

Of course, I have to use a thermopen for reading temperature - and generally test cooled wort between 60 and 70F, so not sure how well the ATC function works on that meter.

The only time I had a test mash measure that far off - I was using aciduated malt and it took nearly 20 minutes for mash pH to rise back to a decent pH. I had gotten distracted (fortunately) and didn't add any pickling lime to adjust right away - it just came back on it's own.

 

[MikeInMKE]

Like anything, this will take some practice, which I will have to do with a mini-mash on a day I'm not planning on brewing.

Thanks for your replies.