Author Topic: pH Meters  (Read 4500 times)

Offline lonetreedavid

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pH Meters
« on: February 09, 2010, 11:07:22 PM »
There was a discussion a few months ago about storing (and calibrating) pH meters.
However, I'd really like recommendations about particular models - especially the Hanna Instruments Beer Testing models.
Any opinions??
thanks

Offline euge

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Re: pH Meters
« Reply #1 on: February 11, 2010, 10:46:40 AM »
Well you want to use the General Hydroponics 7.0 pH calibration fluid for storage.

I haven't owned a Hanna but bought an Ecotester instead. It is waterproof, accurate and only cost me about $75 at the LHS.

Example:

http://www.pulseinstruments.net/index.asp?PageAction=VIEWPROD&ProdID=2884

AFAIK the Hanna's are a popular brand. Costly.
The first principle is that you must not fool yourself, and you are the easiest person to fool. -Richard P. Feynman

Offline Kaiser

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Re: pH Meters
« Reply #2 on: February 11, 2010, 04:11:03 PM »
Is that a pH meter designed for beer? Do you have a model Name/number?

Kai

Offline lonetreedavid

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Re: pH Meters
« Reply #3 on: February 12, 2010, 12:29:36 AM »
This is the link from the Hanna website for Beer pH testers

http://www.hannainst.com/usa/prods2.cfm?id=031003

let me know what you think

Offline euge

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Re: pH Meters
« Reply #4 on: February 12, 2010, 10:02:16 AM »
I don't see why not. I've used it for testing my mash, water etc. As long as I keep it calibrated.
The first principle is that you must not fool yourself, and you are the easiest person to fool. -Richard P. Feynman

Offline mrcceo

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Re: pH Meters
« Reply #5 on: February 12, 2010, 06:42:14 PM »
I can probably help you.  I started with the Hanna 98103 but didn't have much faith in it.  I subsequently purchased a lab quality meter.  I'll run a side by side test tomorrow and post the results for you.

Offline Kaiser

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Re: pH Meters
« Reply #6 on: February 12, 2010, 09:43:21 PM »
How much are those simple Hanna meters? If the precision is only 0.1 - 0.2 units you may be better of using colorpHast strips.

Kai

Offline euge

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Re: pH Meters
« Reply #7 on: February 12, 2010, 11:31:17 PM »
Kai I apologize I didn't read your post fully.

It's an Ecotester pH1 I think it has Oakton guts... whatever that means.

http://www.hydroponicsoutlet.com/Oakton-Meters-Waterproof-EcoTster-pH1-p/ok35423-00.htm
                               
http://www.eutechinst.com/pdt-para-ph-ecotestrph1.html
The first principle is that you must not fool yourself, and you are the easiest person to fool. -Richard P. Feynman

Offline Kaiser

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Re: pH Meters
« Reply #8 on: February 13, 2010, 06:17:50 AM »
For that price you can also get one that has 0.02 pH accuracy. Although it wouldn't have ATC and automatic calibration. But I think that those features are not necessary. Here is something I wrote about selecting a pH meter for brewing: http://braukaiser.com/wiki/index.php?title=PH_Meter_Buying_Guide

Kai

Offline lonetreedavid

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Re: pH Meters
« Reply #9 on: February 13, 2010, 10:18:26 AM »
Thanks for the link to your article, Kaiser.
Do you have other articles that you could please send me links to?

but what's the bottom line on pH meters?
I want a recommendations for a good meter in the $50 range

Offline tom

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Re: pH Meters
« Reply #10 on: February 13, 2010, 11:58:36 AM »
I have had 2 of these: http://www.hannainst.com/usa/prods2.cfm?id=031003&ProdCode=HI 98128  although it was 0.01 accuracy when I got it. The first lasted several years. The second only lasted 1-2 years, but I didn't store it in the storage solution.
Now I have a Milwaukee.
Get the calibrating solution in 16 oz bottles from your local science supply store.
Brew on

Offline mrcceo

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Re: pH Meters
« Reply #11 on: February 13, 2010, 05:30:25 PM »
The results of the test between the bench top meter (Radiometer PH 220) and the Hanna meter 98103 summarizes as follows:
Six samples were tested ranging from a PH of 6.94 to 2.70
Prior to running the test both meter probes were stored wet, in an approved storage solution.
The probes were hydrated/rinsed for 30 minutes; then were calibrated using standard buffer solutions of 4.01 and 7.01. Both meters held stable readings during calibration.
All samples were tested at 21 degrees Celsius and the probes were rinsed between tests and blotted dry.

The bench top meter was able to reach a stable reading within 32 seconds on average. The pocket meter could only obtain a stable reading on lower PH solutions and would often drift for 10 minutes, which was the cut off point for the test s. The difference between the readings of the two meters ranged on average .32 

It should be noted that the drifting of the reading is what initially frustrated me about the Hanna meter.  Although the drift eventually slowed to the point that I was willing to accept the reading I never trusted it and went back to PH test strips before getting the bench top meter. 

Based on my experience I would suggest staying away from the lower priced meters in favor of PH test strips.  If you are going to invest in a meter start by visiting Kai’s website.  He has some very good information on Ph and the meter he’s using.

Hope this was helpful

Offline Kaiser

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Re: pH Meters
« Reply #12 on: February 14, 2010, 06:19:33 AM »
mrcceo,

Thanks for sharing the test results. I assume that during the test the samples were stirred or the probes were agitated. I tend to see drifts too, but only when I don't move the probe. Also, were the samples well buffered? I think the lab grade pH meter really shine when the sample's pH is very weakly buffered. Soft water is a good example. But most solutions we test in brewing are strongly buffered.

David,
Keep in mind that the simple Hanna meters are advertised as replacements for strips. They seem to have a comparable accuracy. Given the precision with which we want to hit the mash pH, 5.3 - 5.6 is good, they should be acceptable. But if you are technically inclined you may look for more accuracy in the future. It is my opinion that a good simple pH meter with buffers and storage solution can be had for under $100. That is the SM101 that I mention in the article.

Kai

Offline mrcceo

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Re: pH Meters
« Reply #13 on: February 14, 2010, 03:10:09 PM »
Kai:
I did agitate the solutions but did not buffer them.  I based the testing procedures on the instructions that came with the Hanna meter since that meter's performance was in question. 

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Re: pH Meters
« Reply #14 on: February 15, 2010, 02:08:03 PM »
I just posted some similar questions in the equipment section, but I'll repeat them here....I'm looking at a Milwaukee pH51 at the LHBS.  According to Kai's buyers guide, I should be looking for an accuracy of .01ish.  If I read this correctly (http://www.milwaukeetesters.com/pdf/pH51.pdf), the pH 51 is only .1?  All I'm really interested in is mash pH, and Kai's writeup implies that might be OK for that that purpose.  Anybody used this model?
Life begins at 60.....1.060, that is!

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