Adjusting Mas pH

When adjusting mash pH, do you add the grain to the heated water, stir and then measure? After the first reading do you then add salts and/or acid to get the desired pH? I have used salts and acid before, but never really tested pH. Or should I adjust my water to say 5.5 at room temp, then heat and add grain and test the pH?

Also, If using crystal or roasted malts and they are added at the end of the mash, is there any need to adjust for pH at that point?

Thanks for the help!

Add grain to heated strike water (or conversely), wait 10 minutes, remove some of the liquid, cool it to room temperature and measure pH. It should be pretty close to target because you should have made acid/alkali/sauermalz as necessary to the grist and or water before doughing in. Guidance on how to do this can be obtained from the Primer or one of the many spreasheets/calculators. Using such guidance it is wise to make a mini mash (small quantity of grist and water) and make pH meaurement on that prior to doing the full volume mash.

Adjusting the water's pH to the desired mash pH takes care of the alkalinity in the water but not the alkalinity or acidity of the grist components. For most beers additional acid will be needed. For beers with a lot of dark malts alkali will be needed.

Very dark grains are added for flavor, not fermentables and thus there will be no conversion and no need to control mash pH for the benefit of the conversion enzymes. pH should be checked, however, to insure that having set the pH properly for conversion of the base malt the extra colored malts don't drop it below where you want kettle pH.

"It should be pretty close to target because you should have made acid/alkali/sauermalz as necessary to the grist and or water before doughing in"

So, I use RO water since my tap water is crap. From my limited understanding that has a pH of 7. Should I acidify the water with 85% phosphoric acid to get a pH of 5.5 or 5.6, then heat the water and add the grain? After that is done check the pH as you stated. I use Bru'n water to adjust my mash, but have never meausred pH so I have no idea how close I was getting.

RO water tends to have a pH lower than 7 because of CO2 it picks up from the air but the pH of the water is really immaterial as it has no buffering capacity. What counts is the pH of the mash. You should make mineral and acid additions to the water (or use sauermalz) as directed by the Primer or based on guidance from some other source and check the pH of a test mash made using the treated water with the grist yoy intend to mash. Or you can hope for the best and skip the test mash but this is a bit chancy as neither the Primer nor the calculators/spreadsheets can guarantee a precise hit on pH. Usually they are 'close enough for government work' however.

Thanks for the info!!

This brings up anoter question I have. I added all of the salt and acid additions to the DI water prior to heating. I calibrated my meter and then chcked the water PH and it was 2.8, which really threw me off since I though distilled water had a ph of 7. I checked the plain DI water I had remaining and it was 4.5. I checked my tap water and it was 7.5, which is correct, so i know the meter is not broken or not calibrated. Does the PH of the DI water mater? Should I wait to add anything until after I dough in and measure my Ph or add my initial salts, then dough in and measure pH?

I added some pickling lime to get the ph in range and while I was mashing the meausred pH was just under 5.3, so it seems to have been ok.

I think the mistake you are making is lowering the pH of your water. Mash pH is more about the makeup of the grist and mineral qualities of the water. Soft water and or all pale malt recipes sometimes don't get down to mash pH, but ALL mashes will have a lower pH than the strike water used. I'd second the advice of making a small "mini-mash" and testing that with your meter to see for yourself. If you use salts like gypsum, epsom and calcium chloride to match your water profile to your recipe, it's unlikely you'll need anything to further acidify the mash...

dixosx said:

Thanks for the info!!

This brings up anoter question I have. I added all of the salt and acid additions to the DI water prior to heating. I calibrated my meter and then chcked the water PH and it was 2.8, which really threw me off since I though distilled water had a ph of 7. I checked the plain DI water I had remaining and it was 4.5. I checked my tap water and it was 7.5, which is correct, so i know the meter is not broken or not calibrated. Does the PH of the DI water mater? Should I wait to add anything until after I dough in and measure my Ph or add my initial salts, then dough in and measure pH?

I added some pickling lime to get the ph in range and while I was mashing the meausred pH was just under 5.3, so it seems to have been ok.

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The pH of the water has little bearing on its suitability for brewing. In this case, when malt is combined with the treated water, it would actually raise the resulting wort pH from the treated water pH. The resulting pH would have likely been somewhere in the 5 range. There may not have been a need to add lime to the mashing water.

Makes sense thanks for the help!!

dixosx said:

I added some pickling lime to get the ph in range and while I was mashing the meausred pH was just under 5.3, so it seems to have been ok.

Click to expand...

As long as you got the pH of the mash to a value in this range you are OK. It is the mash pH that is ultimately important.

The pH of the water itself is immaterial as it is the alkalinity of the water that is important. RO/DI water has alkalinity of essentially 0.

This remark is true for pH's no lower than 4.3. When the pH goes below this, as it did when you added acid, the alkalinity does begin to mount up. A pH of 2.8 implies an alkalinity of approximately -50,000*10^-2.8 = -79. This can be appreciable.

It is OK to add the acid to the mash liquor if you are sure you are adding the right amount. This is best determined by conducting a test mash in which the acid is added to a small mash in increments until the target pH is reached. The amount of acid used in the test mash is then scaled to the size of the whole mash.


Unless you use an inordinately large amount of caclcium salts or a large amount of highly colored malts or both it is likely that you will need some acid depending on the pH you are shooting for. Probably the easiest way to get that is to use 1% w/w sauermalz for each 0.1 pH reduction in mash pH you are seeking.

I agree with the test mash.

After you've brewed 100 or so batches, you'll be able to better predict how the mash may react with your water, I realize since your adding salt to RO water this could change somewhat for you but you get the idea. For example, I brew with my tap water because it's damn good stuff, and when I brew my Guiness clone I know ahead of time my mash pH is going to be too low due to the acid malt and dark specialty grains in the recipe. I actually add the salts ahead of time in this case. Conversely, when I brew my California Common I know how much lactic acid I will need, so I add it to strike water. If I'm brewing a beer and I'm not sure how it will react, I due a very small mash in a jar, or check my pH 10 minutes in and then adjust as needed.

As mentioned above, don't be concerned with the pH of your water, it's only the pH of the mash that matters.

The Brewing Network, and Basic Brewing Radio have episodes on mash pH and mash efficiency if I"m not mistaken. They are free podcasts.