Using PH test strips?

[Bobby_M]

Ok, so I finally got around to caring about mash PH just to learn about it even though my beers are fine. I got the 100 strips of yellowish paper and dropped a sample from my mash right after initial dough in and during my second batch sparge. Both samples appear to be at the 4.6 color.

First, does the temperature of the sample matter? How long should it take to register a stable color?

What if my mash is really 4.6? I've read the wiki and have no idea what it means.

 

[weetodd]

I've been trying to understand this for a few months now and I've learned a couple of things that seem relevant to your post.

I do believe that pH is temperature specific. I have heard Palmer and others say that at mash temperatures, the pH is lower (0.3 - 0.5 if I remember correctly) than at room temperature. The mash pH at mash temperatures should be somewhere between 5.2 and 5.5.

I have the same pH strips and I can't ever tell what they are reading. I've seen people recommend the Colorphast strips which are more expensive but are easier to read and also can be cut so you can get more life out of the pack.

My understanding is that you get ideal conversion rates at the 5.2 - 5.5 pH range (mash temp). If you go lower than that, your efficiency may suffer (this is the one thing that I have found as a consequence of missing pH on the low side, not sure if there are others like off flavors, tannins, fermentability of wort, etc...).

FYI, I've been trying to understand this in the context of adjusting my water to help accentuate the proper flavors in my beer. Some of my beers seem to lack a punch and the flavors are a bit muted. The first couple of tries with building up water has made a difference for me I believe. Palmer's discussion of residual alkalinity is helpful (somewhat for me, I still find it confusing) in the event you've not read through that yet.

 

[Lil' Sparky]

Haven't you been getting really good efficiency? Why the sudden curiosity about the mash pH?

I know temperature makes a difference with pH, but I don't know how it affects the pH strips or even where to tell you to look.

If you mash pH really is 4.6, then it's too acidic (was this a really dark beer?) but my guess is your pH is fine if you normally get excellent efficiency and your beers taste good.

 

[AdIn]

Sorry to disappoint you but I think only this kind of strips provide adequate accuracy: http://pivo.northernbrewer.com/nbstore/action/search-do?searchTerm=ColorpHast

I just submerge one strip to the wort for a few seconds then check against color scale.

 

[Bobby_M]

You're right, the beer is fine and I get 80+%. I just saw these strips for like $3 and added them to my order to play around. No, I'm not paying $30 for those at northern.

 

[Bombo80]

I have used the yellow strips, also. I usually make sure my mash ans sparge water are in line with what I brewing. Normally in the 5.2 to 5.5 range. I will check the mash, from time to time, after my spoon has cooled to room temp.

I have discovered a vast difference in my house water, which I run through a Pur water filter, and the water which I get from a free flowing spring. I don't have my notes, but my tap water is in the 5 range, where the spring water is much closer to 7. Kind of weird. I think I am going to send in a sample, so I can see what the chemical composition of the water is.

 

[david_42]

My frustration with the yellow strips turned me into a pH5.2 supporter. Even a pH5.2 solution reads 4.6 on the strip! I would if anyone has ever written to the manufacturer and told them how worthless their product is. Or is everyone like me and just doesn't think $3 is worth the effort?

 

[mrkristofo]

You should be able to register a stable color relatively quickly. Give it 30s if you're cautious, but I wouldn't worry too much about it. pH strips are a pretty qualitative "measurement" anyway. Temperature will affect the accuracy of the reading you take. Below are the relative errors at 18˚C vs 100˚C:

Indicator 18°C (64°F) pH 100°C (212°F) pH
Methyl violet 0.1 – 2.7 0.5 – 1.7
Methyl yellow 2.4 – 4.0 1.9 – 2.9
Methyl orange 3.2 – 4.4 2.5 – 3.7
Methyl red 4.2 – 6.6 4.0 – 6.0
4-Nitrophenol 5.0 – 7.0 5.0 – 6.5
Phenol red 6.8 – 8.4 7.3 – 8.3
Cresol red 7.2 – 8.8 7.6 – 8.8
Phenolphthalein 8.3 – 10.0 8.1 – 9.0
Thymolphthalein 9.3 – 10.5 8.7 – 9.5

As for $33 for a package of narrow range pH strips, you have to be ****ing insane.

With 30 seconds on Fisher Scientific's website I found these. Pack of 50 of the pH 3.0-6.0 for under $5. OR if you've really got your heart set on the colorphast strips, they're $20

Edited for correctness...Temperature does significantly affect pH strips.

 

[the_bird]

There is a temperature sensitivity to the strips. IIRC from Palmer, readings at mash temp will be higher than those at room temp - and I think the 5.2 target is for room temperatures. In fact, I started panicking the first time I used the strips and read a 5.8, until I re-read Palmer and saw that I needed to be sensitive to temperature.

I just use the cheap strips; I'd buy a meter (even having to buy replacement electrodes periodically) before dropping $30 on strips.

 

[lustreking]

I really like the colorpHast strips. You can get them for $16.42 with free shipping from here.
http://www.sanitationtools.com/Products.asp?Product=1391&Category=72

Much cheaper than from the homebrew stores.

 

[Dr Malt]

Those pH test strips are not dependable or easy to read. :cross: The $33 strips may be better but are a rip off. If you are even considering spending that kind of money for pH measurement, check out the Hanna pHep hand held meters. They start at about $50. I have the Hanna Waterproof pHep pH and temperature meter. It set me back about $100. I know, a little much, but it is great. It measures both temperature and pH and adjust pH for the temperature effects. Being a chemist, I had to get one!!

Dr Malt

 

[clayof2day]

Meters are nice, but the probes do need to be replaced annually. I do think the colorphast strips are overpriced, but they are the only strip that will will give accurate/precise readings in that range. As someone else mentioned, they can be cut lengthwise down the centerline and now you 100 strips. This should last you well over a year and is cheaper than a replacement ph meter probe.

 

[TexLaw]

I'd rather spend money on 5.2 stabilizer than pH strips.


TL

 

[Bobby_M]

yeah, but that's like taking Tylonol before you get a headache.

 

[TexLaw]

I don't mind avoiding headaches, especially at brewtime.


TL