Mash Ph Control

[altstart]

Hi
Recent discusion on the subject of mash PH has prompted me to give more attention to this aspect of brewing. One of the first requirements is to have a PH meter and research has shown that I need a PH meter with an automatic temprature compensation feature. A search of E Bay has revealed that PH meters listed there are totally aimed at the tropical fish tank market and only have this feature from 0C to 50C which is of no use in brewing. Further research has found that there is an alarming rise in price in order to purchase a PH meter that has the required ATC range suitable for mash temps between 60C and 70C. I have come up with the following links http://www.hannameters.com/hi83141.html and http://www.sci-bay.com/catalog.asp?prodid=...;showprevnext=1. Does anyone have information on a more suitable PH meter for this application and where it can be obtained. Is there any interest in a bulk buy.
Cheers Altstart

 

[MHB]

Hanna has one especially made for brewing its model number HI 99151, the sexy orange and blue silicone covers are an optional extra.
Im very happy with mine, not cheap, but well made and good ATC form -5 to +105oC.
Got mine through an American eBay dealer.
MHB

 

[srcossens]

I've got a friend who uses little trial jars when checking his pH. He runs some wort in to the trial jars, closes it up and rolls it around in a small bucket/bowl of water to cool it down sufficiently enough that it won't effect the probe too much. He's got a pH meter with ATC, but just cooling it down slightly will allow the probe to last longer as they can get damaged easily. It only takes about 1 minute to cool it sufficiently and If you did this, you'll be able to get the cheaper ones.

 

[vykuza]

Edit: Beaten. ^^^^ What he said!

I need a PH meter with an automatic temprature compensation feature. A search of E Bay has revealed that PH meters listed there are totally aimed at the tropical fish tank market and only have this feature from 0C to 50C which is of no use in brewing. Further research has found that there is an alarming rise in price in order to purchase a PH meter that has the required ATC range suitable for mash temps between 60C and 70C.

I don't have any experience with PH meters whatsoever. But I presume the sample size is quite small? Would the temperature of the sample not drop down in to that 0-50 (environmental temp) quite quickly and then work in the PH meter?

 

[jasonharley]

I've got a friend who uses little trial jars when checking his pH. He runs some wort in to the trial jars, closes it up and rolls it around in a small bucket/bowl of water to cool it down sufficiently enough that it won't effect the probe too much. He's got a pH meter with ATC, but just cooling it down slightly will allow the probe to last longer as they can get damaged easily. It only takes about 1 minute to cool it sufficiently and If you did this, you'll be able to get the cheaper ones.

+1



5 eyes

 

[ekul]

Why is ATC useful in brewing?

pH does change with temperature, but your mash is going to be at the temperature that you took the reading, so won't it be accurate? If you take a pH reading at 65C, wouldn't you want to know the pH that the mash is at right now, rather than what the mash will be when it is at 20C? pH readings change with temperature because the pH actually changes too ie boiling PURE water is slightly more acidic than water at 20C, but will go back up when cooled.

EDIT This one here has ATC and is only $25 delivered http://cgi.ebay.com/Handheld-pH-Meter-Pen-...=item35a7971de0

 

[MHB]

Mainly so that you can do calculations on what to add to make desired adjustments ATC levels the playing field so to speak.
If you wanted to adjust the pH of a boiling wort by 0.5 pH, you know how strong your acid/base is and the volume in the kettle its pretty easy to work out how many mills to add, having ATC means that you dont then need to adjust the calculated addition for the difference between ambient and the wort.
Or you can be really lazy, add a bit... bit more...bit more...got it
M

 

[ekul]

Mainly so that you can do calculations on what to add to make desired adjustments – ATC levels the playing field so to speak.
If you wanted to adjust the pH of a boiling wort by 0.5 pH, you know how strong your acid/base is and the volume in the kettle it's pretty easy to work out how many mills to add, having ATC means that you don't then need to adjust the calculated addition for the difference between ambient and the wort.
Or you can be really lazy, add a bit... bit more...bit more...got it
M

So its more about the acid/base that you're adding NOT being at the temp of the wort then? So you'd plug in say 100C and the pH meter will tell you what pH the acid/base will be when its 100C, is that right?

I talked to my chem lecturer today (who is also a brewer ) and he said that if you want to know the pH of your wort at mash temps it would be better NOT to have ATC on the pH meter. This is because the pH reading is correct at that temperature, which is also the temperature that the reactions will be happening. I didn't talk to him about the effect of temperature on the acid or base that you're adding, as I hadn't considered it until just then.

An interesting topic to be sure

 

[MHB]

pH does change with temperature, if we made a standardised solution and measured its pH at different temperatures the pH would change, the concentration of ions in solution wouldn't. What we are adjusting is the number of ions not the pH (that's a symptom not the cause) having ATC just makes it easier to work out the right addition, regardless of the temperature of what you are measuring.

And yes it's an interesting question, the more I read up on pH the more convinced I am that its really all (well almost all) about having enough Calcium in there, Residual Alkalinity being a very common approach to the problem on a commercial basis and it really just adjusts for Ca²⁺ and ignores the rest, as you said an interesting topic and one I need to spend a bit more time on.

MHB

 

[ekul]

The concentration of H ions do change with temperature, thats what causes the pH to change. pH is the measure of the amount of hydrogen ions in solution. pH = -log (concentration of H ions) Adjusting ions adjusts pH.

A mash at 65C will have a lower pH than a mash at 20C because of the higher amount of ions in soution. If you measure the pH of your mash at 65C this will be the true pH at that temperature. If the pH meter displays the value that the mash will be at 20C (or any temp except 65C) then you aren't getting the real pH at that moment in time because the amount of dissolved ions, and thus the pH, will change.

I got a real bad flu at the moment, but i think thats what i wanted to say.

BTW. I wanted to add that I don't measure pH or do any water calculations at all. The above is from my knowledge of chemistry, not brewing.


EDITED TO ADD ~ Actually maybe the pH5.2 people are trying to achieve is actually pH5.2 as if the mash is at 20C, kind of like how when we give original gravity we automatically assume that it was a reading taken at around 20C.

pH does change with temperature, if we made a standardised solution and measured its pH at different temperatures the pH would change, the concentration of ions in solution wouldn't. What we are adjusting is the number of ions not the pH (that's a symptom not the cause) having ATC just makes it easier to work out the right addition, regardless of the temperature of what you are measuring.

And yes it's an interesting question, the more I read up on pH the more convinced I am that its really all (well almost all) about having enough Calcium in there, Residual Alkalinity being a very common approach to the problem on a commercial basis and it really just adjusts for Ca²⁺ and ignores the rest, as you said an interesting topic and one I need to spend a bit more time on.

MHB

 

[altstart]

Hanna has one especially made for brewing its model number HI 99151, the sexy orange and blue silicone covers are an optional extra.
Im very happy with mine, not cheap, but well made and good ATC form -5 to +105oC.
Got mine through an American eBay dealer.
MHB

Thanks MHB that link is exactly what I am Looking for. Amazon .com have this meter for USD270.00 but they will not post to Oz. I found the following links very helpful on Mash PH
[post="0"]Overview of ph[/post] [topic="0"]how ph effects brewing[/topic] [post="0"]mash ph control[/post] I found these links in a post on AHB by somebody else but I cannot refind them in order to give proper credit.
Cheers Altstart

 

[MHB]

Got mine here affordableinstrument786

M

 

[Thirsty Boy]

EDITED TO ADD ~ Actually maybe the pH5.2 people are trying to achieve is actually pH5.2 as if the mash is at 20C, kind of like how when we give original gravity we automatically assume that it was a reading taken at around 20C.

5.2 (or thereabouts) is the figure you are looking for if you measure at mash temperature - if you are measuring the pH at about 20 (or if your meter is able to compensate for that large a temp difference) then you need to be looking for a mash pH of more like 5.4

 

[eamonnfoley]

I just bought a Milwaukee MW102 from US via Ebay. Only $105 plus $30 postage. By all accounts a very good unit for a good price. It has auto calibration and ATC, but you dont even need those functions. the MW101 is about $75, and a good portable unit with a probe.