Measuring pH

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BrewerDon

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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?
 
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.

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.

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.

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.

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.

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.

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.
 
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°
 
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.
 
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