Ph Strips

[Benniee]

Take a look at the attached pic. Is a pH strip that I tried to use today to measure my mash pH.



My process was to draw off a small amount from the mash and let it cool - use the sample to take a gravity reading, then dip the pH strip in there, left it for around 30 seconds. When I pulled it out I took a pic. From what I can guess the small section right near the arrow is the pH of the sample. The other colours are there as a reference.

My sample section doesn't even appear to be close to the colours :huh:

Is my process for using the strips wrong? Or is my mash pH so far out of whack that the strips can't cope?

I'm thinking I might have to invest in a little digital pH meter.

Benniee

 

[buttersd70]

the sample area is actually the larger square between 5.9 and 6.1. The arrow on these strips had me going for a bit, as well, so I tested one in a clear pH 6 solution, and got the right colour on that square. The bit on the strip where the arrow points was only off white.

 

[Simon W]

I thought the middle panel (between 5.9 and 6.1) was the test panel?
I'd guess you're around 5.0pH
edit: eep, I shoulda hit refresh before posting.

 

[LethalCorpse]

You're gonna need test strips designed for a wider range of pH, or a digital pH meter (which, believe it or not, is pretty cheap these days)

 

[Benniee]

Thanks guys - I feel like giving myself a head slap right now.

It seems obvious now that someone has spelled it out to me.

Looking at my pic again I can see that the square in the middle has turned a light yellow.

Benniee

 

[Ross]

Thanks guys - I feel like giving myself a head slap right now.

It seems obvious now that someone has spelled it out to me.

Looking at my pic again I can see that the square in the middle has turned a light yellow.

Benniee

Looks like your PH is below 5.2 from the pic, unless it's changed over time.
Just dip the strip in the wort for a few seconds & then remove & read.

cheers ross

 

[matti]

Looks like your PH is below 5.2 from the pic, unless it's changed over time.
Just dip the strip in the wort for a few seconds & then remove & read.

cheers ross

All assumption B)
get a strip with a lower range. i.e pH 4-7
I run off some wort after 60 minutes, dip wet it for 2-3 second while still hot, get the result in 30 seconds.

 

[katzke]

Have not used them yet. Form what I have read the PH should be taken at room temp as if it is taken at a higher temp it will be different.

Are the strips different?

 

[buttersd70]

Temperature will make a difference to pH, however my understanding of it is that a/ the difference in a pH5 buffer solution between 20C and 60C is <0.1, which is well outside the accuracy of strips, anyway, and b/ you are interested in knowing what the pH of the mash is during the mash, so the pH should be taken at mash temperature.

 

[goatherder]

There is about 0.3 pH difference between mash temp and room temp. When you take a measurement at mash temp the small volume on the strip is rapidly cooling. This makes it hard to determine what the temperature of the sample is and hence the pH. Although it takes a little longer, you will get more accurate and repeatable results if you take a small sample from the mash, cool it to room temp and test the sample. The same advice applies to pH meters - I have heard that probe life is shortened by exposing them to hot liquids.