Spike Brewing 12.5 Conical Fermenter Giveaway!

Home Brew Forums > Home Brewing Beer > Brew Science > Measuring pH

Reply
 
LinkBack Thread Tools
Old 02-08-2012, 08:58 PM   #1
BrewerDon
Feedback Score: 0 reviews
Recipes 
 
Join Date: Nov 2011
Location: Dallas, Texas
Posts: 87
Liked 6 Times on 5 Posts
Likes Given: 5

Default Measuring pH

I want to make better use of my pH meter.

I have had my water analyzed and before brewing I use one of the common spreadsheets to help me come up with a plan to treat my water. On brew day, I take a sample, cool it to room temperature, measure the pH, and add that info to my notes. If any further adjustment is needed, I've been doing that on the next batch.

I want to start adjusting the "current" batch not the "next" batch.

The wiki page, "Understanding Mash pH" says to take the pH measurement shortly after dough-in. "Shortly after" is sort of vague. I have seen posts here where people say to take the measurement 20 minutes after dough-in. I've also seen people say to make small adjustments at a time.

So let's say I'm brewing an infusion mash with no protein rest and my conversion temp will be in the upper 150s where conversion may be complete in 45 minutes: I make my infusion. I wait 20 minutes before taking a sample. Then I quickly cool my sample. Then I take my measurement. Then, I finally make my adjustment. Wait some more. Oh no, the adjustment isn't enough. Take another sample. Cool it down. Measure it....
It seems like I am now quite a ways into the conversion with the wrong pH.

What do others do? Do you always do an acid or protein rest just so you can have a chance to adjust pH? Or, perhaps you don't wait 20 minutes. Help me out here.

What is your pH adjustment process?

Is your process different depending on the mash schedule?

__________________
BrewerDon is offline
 
Reply With Quote Quick reply to this message
Old 02-09-2012, 03:52 AM   #2
ajdelange
Senior Member
HBT_LIFETIMESUPPORTER.png
Feedback Score: 0 reviews
Recipes 
 
Join Date: Aug 2010
Location: McLean/Ogden, Virginia/Quebec
Posts: 5,805
Liked 563 Times on 464 Posts
Likes Given: 15

Default

Quote:
Originally Posted by BrewerDon View Post
I have had my water analyzed and before brewing I use one of the common spreadsheets to help me come up with a plan to treat my water. On brew day, I take a sample, cool it to room temperature, measure the pH, and add that info to my notes. If any further adjustment is needed, I've been doing that on the next batch.
That's really the best way to do it. With experience you should know what to expect to within 0.1 pH (without the use of calculators or spreadsheets). If you are doing something quite different from anything you have done before or if variations in your water or other materials are causing your predictions to be off more than that then probably the best approach is a test mash in which you take about a pound of grist and bring it to the temperature of your first rest with the water you intend to brew with, let it rest and then check the pH of a cooled sample. If your water supply's alkalinity varies substantially over short periods (usually because the supplier ties into different sources under different seasonal and demand conditions) then you should obtain an alkalinity test kit and check before each brew.

Quote:
Originally Posted by BrewerDon View Post
I want to start adjusting the "current" batch not the "next" batch.
This shouldn't be necessary. Every mash should not be a titration. Give yourself some tolerance. If you are shooting for 5.5. and get 5.6 or 5.4 that's OK. Just make a note to use a little more or less acid next time you brew this beer.

Quote:
Originally Posted by BrewerDon View Post
The wiki page, "Understanding Mash pH" says to take the pH measurement shortly after dough-in. "Shortly after" is sort of vague. I have seen posts here where people say to take the measurement 20 minutes after dough-in. I've also seen people say to make small adjustments at a time.
As soon as dough-in is complete you can take the first sample. But then take a few more over the course of the first rest. The readings will usually be pretty stable except in cases where you have used sauermalz. I that case the initial pH may be low (alarmingly so) and then gradually rise over the next 20 minutes or so.

Quote:
Originally Posted by BrewerDon View Post
So let's say I'm brewing an infusion mash with no protein rest and my conversion temp will be in the upper 150s where conversion may be complete in 45 minutes: I make my infusion. I wait 20 minutes before taking a sample.
Start taking samples as soon as you are doughed in. Then take another one after 5 minutes and another at 10. If the pH is moving towards target then relax and keep taking measurements every 5 - 10 minutes. If it is clear that the target will be reached in 20 minutes then you are fine. If it is clear that it won't then add more acid or base as necessary. I wouldn't use sauermalz for the acid (use lactic or phosphoric instead) and I wouldn't use chalk for base. Use lime. But add very small amounts and then look for the trend in time again. If you are within ± 0.1 then don't worry. The last thing you want to wind up doing is adding acid, then base, then acid again.

Quote:
Originally Posted by BrewerDon View Post
What do others do? Do you always do an acid or protein rest just so you can have a chance to adjust pH? Or, perhaps you don't wait 20 minutes.
I usually brew lagers which are doughed in cold. With ales I usually do a beta glucan rest so I do have the opportunity you refer to.

Quote:
Originally Posted by BrewerDon View Post
What is your pH adjustment process?
Even with uniform water (I use RO with salts) and familiar materials I sometimes get a surprise but it is rare that I miss by more than 0.1. I keep acid handy in the brewery because I have never undershot pH. If it's needed I add a couple of mL, stir, wait 5 minutes and check again. If more is needed I add more. I don't think I've ever had to make more than 2 additions.

Quote:
Originally Posted by BrewerDon View Post
Is your process different depending on the mash schedule?
No, not really. Whether it's a decoction mash doughed in at room temperature or an ale doughed in at beta glucan or protein rest temperature I always take the readings at dough in. In the lagers I use sauermalz and never need to make adjustments. It's with the darker ales that I sometimes do.
__________________
ajdelange is offline
 
Reply With Quote Quick reply to this message
Old 02-09-2012, 03:52 PM   #3
BrewerDon
Feedback Score: 0 reviews
Recipes 
 
Join Date: Nov 2011
Location: Dallas, Texas
Posts: 87
Liked 6 Times on 5 Posts
Likes Given: 5

Default

Thanks for the very thorough response! I really appreciate it.

__________________
BrewerDon is offline
 
Reply With Quote Quick reply to this message
Old 02-15-2012, 07:45 PM   #4
terrapinj
HBT_SUPPORTER.png
Feedback Score: 1 reviews
Recipes 
 
Join Date: Dec 2010
Location: Santa Monica, CA
Posts: 2,412
Liked 167 Times on 124 Posts
Likes Given: 533

Default

AJ - I still have some confusion about the temperature for pH samples

i know that at mash temps ~ 150 the pH will be about .3 higher than at room temp

i've been reading my samples ~68° but am now curious if I should be adding ~.3 to get the actual pH of the mash or if I should be reading at mash temps

if the pH reads 5.2 at 68° would the actual pH of the mash be ~5.5?

i know the broad target range is ~ 5.2-5.7 but is that pH at room or mash temps?

why would we read the pH at room temp if we are trying to measure the pH of the mash which is ~150°

__________________
terrapinj is offline
 
Reply With Quote Quick reply to this message
Old 02-15-2012, 08:00 PM   #5
MNDan
HBT_LIFETIMESUPPORTER.png
Feedback Score: 0 reviews
Recipes 
 
Join Date: Apr 2009
Location: Minnetonka, MN
Posts: 340
Liked 13 Times on 10 Posts
Likes Given: 8

Default

Mashes have a pH that is .2-.3 LOWER at mash temp vs. at room temperature. Desired pH is usually around 5.2, as measured at mash temp, so look for around 5.4-5.5 at room temp.

__________________
MNDan is offline
 
Reply With Quote Quick reply to this message
Old 02-15-2012, 08:08 PM   #6
MNDan
HBT_LIFETIMESUPPORTER.png
Feedback Score: 0 reviews
Recipes 
 
Join Date: Apr 2009
Location: Minnetonka, MN
Posts: 340
Liked 13 Times on 10 Posts
Likes Given: 8

Default

This is a good read FWIW -

http://braukaiser.com/blog/blog/2011/03/02/about-ph-targets-and-temperature/

__________________
MNDan is offline
 
Reply With Quote Quick reply to this message
Old 02-15-2012, 08:48 PM   #7
terrapinj
HBT_SUPPORTER.png
Feedback Score: 1 reviews
Recipes 
 
Join Date: Dec 2010
Location: Santa Monica, CA
Posts: 2,412
Liked 167 Times on 124 Posts
Likes Given: 533

Default

thanks for the correction and the link!

__________________
terrapinj is offline
 
Reply With Quote Quick reply to this message
Reply


Quick Reply
Message:
Options
Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Measuring SRM swankyswede Brew Science 29 04-11-2014 11:41 PM
Measuring P.P.G. hector Brew Science 24 03-25-2011 12:10 PM
Measuring carbonation HairyDogBrewing Brew Science 1 02-22-2011 07:54 PM
Measuring Mash PH Steven9026 Brew Science 26 12-08-2010 05:14 PM
Measuring calories in beer Rimshot Brew Science 8 03-25-2010 02:21 AM