Proper use of PH test strips? - Page 2

**ajdelange** · 05-29-2011, 08:38 PM

See #7. The probability that I am color blind is 100%. I don't do elf hat blue or rose blue. I'm lucky if I can tell it's blue. I'm relying, therefore, I what I see reported. Kai Troester did some extensive testing on these things. You'd have to refer to his website to see about the grade of strips he used. He asked several people to assist him in assessing his results and he did this by photographing strips exposed to various levels of pH next to the scales printed on the bottles, e-mailing these to us and asking us to read them. I couldn't do that, of course, but what I could do was analyze the colors in the photos, construct a calibration curve from the scale and "measure" the pH of the individual strips from that. They were way off RE pH meter readings Kai made.

If you know of strips that do compare favorably to pH meter readings of mash please let the other 95% (i.e. normal color vision) of the readership know what they are.

**remilard** · 05-30-2011, 12:55 PM

Quote:

Originally Posted by ajdelange

See #7. The probability that I am color blind is 100%. I don't do elf hat blue or rose blue. I'm lucky if I can tell it's blue. I'm relying, therefore, I what I see reported. Kai Troester did some extensive testing on these things. You'd have to refer to his website to see about the grade of strips he used. He asked several people to assist him in assessing his results and he did this by photographing strips exposed to various levels of pH next to the scales printed on the bottles, e-mailing these to us and asking us to read them. I couldn't do that, of course, but what I could do was analyze the colors in the photos, construct a calibration curve from the scale and "measure" the pH of the individual strips from that. They were way off RE pH meter readings Kai made.

If you know of strips that do compare favorably to pH meter readings of mash please let the other 95% (i.e. normal color vision) of the readership know what they are.

Kai's testing was on EMD Colorphast strips which are commonly sold by homebrew shops as high precision strips. At least they don't call them high accuracy.

**Homercidal** · 05-31-2011, 02:44 PM

I was going to give it another go on the last brewday, but forgot. At this point I'm going to shoot for a digital tester, but I might try the strips out again before I get it. Maybe the next brew day I will not be pushed for time and will be better prepared to use the strips.

I do not have the colorphast, which I suspect will be better than the generic brand I have. The price of colorphast strips is a good portion of the price of a lower-end digital pH meter.

a10t2 · 05-31-2011, 03:01 PM

Quote:

Originally Posted by Homercidal

I do not have the colorphast, which I suspect will be better than the generic brand I have. The price of colorphast strips is a good portion of the price of a lower-end digital pH meter.

The generic ones are pretty much worthless IME; all they can tell you is the color of the wort. The ColorpHast strips (based on the survey Kai did, and in which I participated) can be read with reasonable precision, and are fairly accurate once the appropriate offset (+0.3 pH) is applied. This would appear to be some peculiarity of mash chemistry rather than a flaw in the strips' manufacture, since they are accurate in buffer solutions.

You're right that they are a little pricey; by the time you use 300 ColorpHast strips you could have bought a mid-grade pH meter. I would submit that for a home brewer the strips are a practical alternative. At work where I brew 2-3 times a week I maintain a pH meter, but at home where I brew 10-15 times per year I don't personally think it's worth it.

**Homercidal** · 05-31-2011, 03:24 PM

Yeah, I am still debating with myself over the cost. At least with a pH meter, I can get better resolution and higher accuracy than with the strips. And I can test my starting water rather than relying on the lab report, which may not be accurate at any given season. Plus, it's one more cool toy to own.

But there is expense beyond just the purchase of the meter, like buffer solution and calibration solution. And I've heard that they can just suddenly "go bad", which would suck.

**pjj2ba** · 05-31-2011, 04:05 PM

test them with some vinegar and a solution of baking soda and water. You should definitely see some changes with those

wildwest450 · 05-31-2011, 05:53 PM

Quote:

Originally Posted by Homercidal

But there is expense beyond just the purchase of the meter, like buffer solution and calibration solution. And I've heard that they can just suddenly "go bad", which would suck.

Stop whining and man up, ph meters are cool! Who want's to guess the color of some cheesy ph strips when you can see an actual lcd readout telling you how awesome you are.

If you can get in on some "bulk" grain buys, I got a crapload of calibration solutions for real cheap. The buffer and cleaning solution I bought will last nearly a lifetime, so it's a onetime expense.

_

SwampassJ · 07-16-2011, 03:56 PM

Bumping since I didn't know better before I bought them. $5 pH strips are useless in anything we would use them for.

RCCOLA · 07-17-2011, 01:02 AM

Here's a pic of my strips after being dipped in wort which read 5.6 on my calibrated digital pH meter.

**Stevo2569** · 07-17-2011, 01:15 AM

Quote:

Originally Posted by wildwest450

Stop whining and man up, ph meters are cool! Who want's to guess the color of some cheesy ph strips when you can see an actual lcd readout telling you how awesome you are.

If you can get in on some "bulk" grain buys, I got a crapload of calibration solutions for real cheap. The buffer and cleaning solution I bought will last nearly a lifetime, so it's a onetime expense.

_

WEST
What Ph meter do you have? Ive been looking for a cheap but good one.