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Old 11-19-2010, 06:08 PM   #1
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So I bought a tube of test strips and after trying them out twice in my mash, I find that they do nothing.

Yep, the color pad looks like a wet pad. No change in color that I can detect. To me this can mean 3 things:

1. I am stupid and don't know how to use the strips.
2. My PH is off the charts.
3. The strips don't work.

All of the colors on the comparison chart are in the range for beer and they are all different enough from the plain strip to make me believe that if the strips were working, and the mash was anywhere near the proper acidity, I'd see a change.

 
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Old 11-19-2010, 06:11 PM   #2
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Did you buy the cheap ones or the good ones? I bought the good ones from a lab-supply store ($20 instead of $40), and they clearly change color - BUT - and this is a big but - as per a pretty accurate pH meter, their reading is off by a decent amount (about 0.2, maybe 0.4).
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Old 11-19-2010, 06:13 PM   #3
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Mine change color and my mash usually falls in the 5.2-5.6 range according to color, as far as how accurate they are? i would have no idea.

 
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Old 11-19-2010, 07:14 PM   #4
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I think I bought them at Siciliano's Market in Grand Rapids. I bought them and forgot to use them that batch, then didn't brew for a while and forgot I had them. Got them out for the last batch and was disappointed to see nothing happen. Then tried again with some starsan solution thinking that surely I'd see SOMETHING change, even if it wasn't in the range of the strip.

 
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Old 11-20-2010, 03:55 AM   #5
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Usually only one end of the strip will actually register a reading, the rest is a just a heavy paper. Make sure you are dipping the correct end in the mash.

 
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Old 11-20-2010, 08:52 PM   #6
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Last year I bought those exact same strips from the exact same LHBS (sicilianos) and got the exact same results you did. I'm not sure what's wrong with them (or us). I have a pH meter now.
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Old 11-20-2010, 09:51 PM   #7
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Quote:
Originally Posted by -TH- View Post
I'm not sure what's wrong with them (or us).
Well, the probability that one or the other of you is color blind is 9.5% but the probability that you both are is 0.25% so I guess that's probably not it.

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Old 05-29-2011, 04:47 PM   #8
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Instead of starting a new thread I'll go with this. I bought the colorphast PH 4.0 - 7.0 strips. If I dip them in lemon juice or beer the color will drop to the 4.0 scale which is fine. If I dip them in Portland tap water I don't see a perceptible change in color. As far as I know Portland adds sodium hydroxide to try and maintain 7.8-8.0 ph in the water. So I should see the color at the 7.0 scale. The last time I brewed I used them and did not notice much of any color change.

Am I doing something wrong? Do you think they are defective or the wrong strips in the box or should I just toss them out and buy yet another device?


edit - dunked a strip in Ammonia and it immediately hit the 7.0 color so the strips work on the extremes but not very well in range.

 
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Old 05-29-2011, 07:55 PM   #9
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Strips aren't of much use in brewing. Do a search and you will find innumerable references to their shortcomings (including in this thread). I'd venture the hypothesis that strips have done more harm to home brewers than good.

The accompanying good news is that the prices of pH meters have gone way down while their performance has gone way up.

 
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Old 05-29-2011, 08:24 PM   #10
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Lab grade pH test strips are reasonably accurate. Keep in mind that error will be introduced from you trying to determine if the color changed to elf hat blue vs rose blue vs Na'vi blue.
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