Measuring Ph of mash and temp corrected readings

[ajdelange]

AJ, don't know whether you'd be willing to opine (I'd understand if not), but would you put the Extech into the class of cheap, undependable meters?

I don't know anything about it and thus cannot say one way or the other.

Do you have a recommendation for a portable one, a good one for brewday when one can't conveniently walk to the lab bench?

A lot of people here like the Hach pH Plus. There is a similar Omega product which some people here have reported favorably on. Hanna has a relatively new offering especially for brewers (titanium body) that works through your smart phone which at first look seems good. The other meter that a lot of people here use is the Milwaukee MW102 but that is a benchtop meter (of comparable price).

 

[Gadjobrinus]

I don't know anything about it and thus cannot say one way or the other.
A lot of people here like the Hach pH Plus. There is a similar Omega product which some people here have reported favorably on. Hanna has a relatively new offering especially for brewers (titanium body) that works through your smart phone which at first look seems good. The other meter that a lot of people here use is the Milwaukee MW102 but that is a benchtop meter (of comparable price).

Thanks AJ. I haven't had a chance to read your lengthy work of yesterday or the day before, hit with some bad news which has slowed me some, but I do intend to go through it. Just a query on the milwaukees - these appear portable to me. Are there other MW102s that are dedicated bench models, or are these the ones you meant?

 

[ajdelange]

The MW102 is distinct from the others I mentioned in that it is not a 'pen' style meter. The 102 lies on the bench and a connected electrode is immersed in the samples. In the pen style the electrode is integral to the body of the meter. But it is certainly not so heavy or bulky one cannot carry it around.

 

[Gadjobrinus]

OK, gotcha. I think I was confused because I've seen people walking around with electrode styles, too. And I'm probably thinking of a permanently mounted, seriously expensive bench instrument, because that's what my friend had (I can't recall, unfortunately - I've been trying).

edit: I originally said "walking around with pen styles." I meant electrode, as you described, AJ.

 

[day_trippr]

fwiw, I've been using a Hach PocketPro+ for almost a year and it's been quite well behaved.
While its construction is fairly crude compared to the Hanna pHep98128 (also a "pen" style) that I've basically retired due to its calibration issues the Hach's performance has been very good.

Also fwiw, a friend brought over his Milwaukee O2 meter that from across the room appears physically identical to their pH meter. The probe and its extraordinarily oversized cable was a pita compared to a pen. (The meter wouldn't calibrate which is why it was brought to me but that's a whole 'nuther issue)...

Cheers!

 

[rhys333]

You have purchased a meter that is intended to be calibrated with NIST standard buffers. These are rarely used except in the laboratory. Most meters use NIST traceable 'operational' buffers. With them if the meter sees, during cal, a buffer near 7 it assumes it is a NIST traceable operational buffer and proceeds to do the calibration based on pH values for that meter stored in its memory. If you present such a buffer to your meter it will assume that it is a NIST buffer and proceed to calibrate presumably based on the tables for that buffer unless you tell it that the pH is something different which apparently you must do. Now what I can't tell from the manual is how this entry is treated with respect to temperature variation. Are you supposed to enter the pH of the buffer printed on the bottle label or the pH at the calibration table as obtained from the table often furnished with the buffer?

I would be a little skeptical about readings obtained with this meter (though the error is probably appreciably less than 0.1 pH) and would caution others to avoid it because of this.

It's not the ideal situation by any means but yes, you should do this. Better would be to buy NIST buffers (https://www.inorganicventures.com/productdisplay/ph-686-standard-0) and calibrate the meter as it is intended to be calibrated.

Thanks for explaining and sorry for my late response. I wanted to test this again on brew day before reporting back. I'm attaching images of the user manual pages which suggest to adjust calibration manually if the buffer solution isn't NIST. Today I tested it both ways. When I manually adjust the readout up to 7.02 (as per the table on the buffer solution) I get 5.49 on my wort sample. When I let the meter autocalibrate to 6.88 (NIST), I get 5.41 instead. A significant difference, however the meter locks in quickly each time and doesn't vary from these numbers. The meter seems to be reliable (or at least consistent), so I'll look into buying NIST 7.0 solution and until then continue adjusting to 7.02 as you suggest. I need to have another chat with the Thermoworks technician too.

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[frettfreak]

Wow. Did not expect this much discussion on the topic but it has been a great lesson for sure! You guys are awesome!! Really appreciate all the input.

I think then, just for fun, I will do as AJ suggested and measure At mash temps, and a few on the way down to a room temp reading just to see what the slope is. Assuming (based on what I think I understood), the slope is going to change on every mash though, and this will not be for anything but interesting data.

FWIW, I have a blue labs bench style meter but am due for an upgrade (the pH resolution not good enough)... That new Hanna Halo looks light tempting! love the techie aspect of it all!!

 

[dantheman13]

There are some interesting claims in the recent BYO magazine in the "help me Mr. Wizard" section, which focuses on why they recommend taking mash pH readings at mash temperature. Obviously, I can't post the article here, but the author makes the claims that the sited literature collected by John Palmer has these values:

Bamforth's range: 5.3 to 5.8 (mash temp) / 5.55 to 6.05 (room temp)
Brigg's range: 5.2 to 5.4 (mash temp) / 5.45 to 5.65 (room temp)
Kunze's range: 5.25 to 5.35 (mash temp) / 5.5 to 5.6 (room temp)

I don't have access to the Bamforth or Kunze data, but I do have the Briggs data. The Briggs data is collected from various sources, and they make guesses as to what temperature the mash pH was taken in some of those data sets, so they are somewhat useless here.

The BYO article didn't look at Narziss's data, which Kai interprets as being taken at room temp:

http://braukaiser.com/wiki/index.ph...iency_in_single_infusion_mashing#mash_results

 

[Teesquar]

Dan, you beat me to it. I received my BYO mag yesterday and read through that article, thinking, "Great, more ranges to consider at mash and room temps".

Came back to this thread just as a reassurance and had to laugh at Silver's first line in post #4, "This issue seems to repeat itself periodically, and is often fueled by brewing magazine articles."

TBH, for a majority of my recipes, I'm just going to zone in on 5.4 and RDWHAHB

 

[Morrey]

Do some of the popular ph meters such as Hach Pocket Pro + take mash temp readings and adjust for temperature variations?

 

[ajdelange]

It has to get from mV to pH somehow. If it is a digital meter it does that by inserting mV into an equation. That equation needs to know slope, offset, temperature and isoelectric pH. If the meter has a temperature sensor (the Hach does) then it is using that to calculate slope and offset from temperature and known buffer pH's. It assumes isoelectric pH is 7.

Short answer: yes.