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Old 12-05-2013, 11:35 PM   #1
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Default Revised buying guide for pH meter (based on the book Water)

It seems that there is need for a revised buying guide for a pH meter based on the specs outlined in the book, Water: A Comprehensive Guide for Brewers, by John Palmer and Colin Kaminski.

Here are the recommended specs in the book (pg. 244):

  • +/- 0.02 pH accuracy
  • ATC (Auto Temperature Control)
  • Two-point calibration
  • Sealed or refillable electrode with a resolution of +/- 0.02 pH or smaller
  • Double junction electrode
  • Flushable junctions, which allows for easier cleaning and longer life

There is a great thread on HBT by Kaiser from 2009 that had recommendations, but it seems fitting to list some new recommendations based on this recently published book.

Feel free to reply below with recommended pH meters that meet these minimum specs.

For easy reference, I'll update possible options here as this thread develops:
Hach Pocket Pro+ ($110+17 shipping) - Recommended by ajdelange here.
OMEGAETTE PHH-7011 ($95+ unknown shipping. Includes case and pH buffers). Recommended by kerklein2 here.
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Last edited by ocluke; 12-16-2013 at 05:39 PM. Reason: added pH meter options
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Old 12-06-2013, 04:35 AM   #2
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I know the books are still warm from the press but even so I'd change a couple of things in those recommendations

1) You ought to be able to get 0.01 pH accuracy* for a surprisingly low price today. If you can do so.
2) ATC is still on the list not so much because you need ATC as because its presence tells you that the meter is digital (absence of manual calibration potentiometers tells you the same thing.
3) Two point calibration is a must have
4) In order to have 0.01 or 0.02 accuracy the meter will have to have 0.01 resolution so that is a must. This is a property of the meter - not the electrode.
5) I'm replacing the double junction requirement with the broader 'junction design suited for brewing'. Double junctions used to be important in brewing because of the formation of silver/protein complexes in single junction designs. This problem seems to have been solved. I discovered the other day that none of the electrodes I use with success in brewing are actually double junction designs and yet they perform in the brewing environment.
6) Renewable junctions are a plus but they add a lot to the cost of an electrode and don't seem to be as necessary as they used to be. IOW I think there have been some breakthroughs in electrode design and I think they have been in the junctions.

Now I'll add a couple more requirements

7) Stable electrode. This means that readings don't wander all over cock Robin's barn within a few minutes of calibration. This is a major problem with some inexpensive meters.
8) Related to 7) is the ability to tell the meter when to accept a calibration reading. (I've been experimenting with a Hanna pHep that is actually quite stable but it decides when to accept the calibration reading and does so too soon so that the meter is not properly calibrated.

8)Isoelectric pH within 1/2 pH unit of pH 7. This is a 'nice to have' as you can correct readings from meters that have isoelectric pH that doesn't meet this spec. This effectively opens up the range over which ATC works properly.

9) Long electrode life. A good electrode will last for 3 or more years.

Hach has a new low cost meter out. It appears to meet all these requirements (except 7 and, as its new, no hint as to how it might do RE 9). Some performance data is at http://www.homebrewtalk.com/f128/fir...er-apa-443205/

*This means the error contributed by meter and electrode is at the 0.01 pH level demonstrable by calibrating and then reading the calibration buffers over time and temperature. RMSE should not exceed 0.01 pH over a small but finite temperature band. This does not mean absolute accuracy as the buffers themselves introduce error of, typically, a bit less that 0.02 pH.

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Old 12-06-2013, 01:47 PM   #3
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I was looking at the new hach meter and it looks good, the only concern I have is the temperature range only goes to 120f. Could be a problem checking mash pH.

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Old 12-06-2013, 03:37 PM   #4
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And that is, among other reasons, why we don't check mash pH at mash temperature (i.e. stress on the electrode). The other reasons are that as commercial brewing operations don't check at mash temperature the literature contains mostly (but not always and it often isn't clear) reference to pH referred to or measured at room temperature. In the extensive discussion of mash pH you see in these fora the measurements are taken, or referred to room temp. All the pH prediction programs/calculators/spreadsheets refer to room temp. Etc.

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Old 12-06-2013, 03:42 PM   #5
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Ok that makes sense, at what temperature should we check pH level at? How do you cool your sample quickly so that mash adjustments can be made if needed? An ice bath?

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Old 12-07-2013, 02:28 AM   #6
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I will look into the Hach meter. Thank you.

The other one I've seen mentioned is the OMEGAETTE PHH-7011, which at $95 for the pH meter, a a carrying case and buffer solutions, it seems like a good (maybe too good to be true?) deal. Any thoughts on this pH meter?

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Old 12-07-2013, 04:35 AM   #7
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Quote:
Originally Posted by molson View Post
Ok that makes sense, at what temperature should we check pH level at?
Room temperature. 20 °C.

Quote:
Originally Posted by molson View Post
How do you cool your sample quickly so that mash adjustments can be made if needed? An ice bath?
Various ways. One guy here puts a shot glass in the fridge or freezer and adds enough sample that it cools to room temperature. I put the sample in a small (4") saucepan and float that on cold water in the sink.
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Old 12-16-2013, 09:04 AM   #8
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I'm now down to the Hach Pocket Pro+, or the OMEGAETTE PHH-7011.

It would be great to hear if anyone has tested the Omega.

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Old 02-06-2014, 03:00 AM   #9
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Default which one did you go with?

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I'm now down to the Hach Pocket Pro+, or the OMEGAETTE PHH-7011.

It would be great to hear if anyone has tested the Omega.
Did you end up going with one of these? If so what was the deciding factor and how do you like it?
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Old 02-06-2014, 09:12 PM   #10
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Quote:
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Did you end up going with one of these? If so what was the deciding factor and how do you like it?
I'm actually ordering today. I want to order the Omega because it seems to be as good of a product for a better deal with a much less expensive replaceable sensor, but having not seen any tests on its real world performance, I'm going to order the Hach per ajdelange's recommendation and testing.

I considered the Hach Pocket Pro+ Multi 2 Tester because it has TDS (I use RO water) and other metering all in one place, but I haven't seen anyone recommending that meter and it adds $63 to the price. My RO already has an inline TDS meter, so I'll just monitor that.
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