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Opinions on my mash PH

I’ll try keep this short.

Been brewing for 2-1/2 years. Went AG after about 6 months. I brew various styles and they all turn out great. I do think that my lighter ales could improve so I decided to check what was in my water. I have a well and I found that my water is very hard and has very high alkalinity. So now knowing my water profile I purchased a Milwaukee MW 102 ph meter and downloaded brun water.

After looking over brun water for the last month I finally had somewhat of an idea of what to do.

Today I brewed a black IPA so prepped my mash water (and sparge water afterwards) making the additions and dilutions per brun water.

When I plugged the grain bill into brun water I diluted my well water with RO water 50/50 and then added gypsum and phosphoric acid to get me at a 5.5 mash ph per brun water

So after 20 minutes I drew off a sample of wort, cooled it to room temp and checked it with the ph meter (yes it was calibrated). The meter measured the ph at 4.45

I personally don’t trust the meter. What do you guys think???

I did check the wort with test strips and they would suggest it was at least a 5 ph but less than 6

I would appreciated your thoughts.


Could be a bad electrode? That’s a reliable meter, so assuming it was able to calibrate, it shouldn’t be that far off. How good are your calibration solutions? How old are your test strips?

Test strips, meter and solutions are all about 5 weeks old. The meter seems to get to the solution ph values ok, Takes a little time but it gets there. In tap water it takes for ever, the reading never seems to settle down. Also it reads my tap water ph at about 6.5 when I’m pretty sure it about 8

Does it measure pH properly in each calibration solution? Are you using the 4.0 and 7.0 buffers?

Used 4.0, 7.0 and also 10.0

In the 10.0 it reads about 9.7

In the other 2 solutions it’s pretty accurate.

I think you’ll be more accurate measuring your mash pH if you just do the two point calibration at 4.0 and 7.0. The higher pH calibration may be throwing off the measurement. I’ve never calibrated mine for 10.0, just the two point.

Where did you get your well water tested?

Did you check the water pH with your meter before starting on brew day? Did it match your well analysis?

Are you sure you used the same % phosphoric that was plugged into brunwater?

Also, ph takes about 15 minutes to stabilize. If you take a sample early enough, it will give you a different reading than what you’d get later. Not sure about that meter, but some are sensitive to higher temps. I’ve never felt with well water, but is it very stable. I mean if it rains heavily does the chemistry change at all?

Try using It’s actually very easy to use. That’s all I mess with

Just seems odd to begin with of adding acid to correct for pH when you already have black malt that will acidify yer mash… Sneezles61

I tested the water using Lamottes brewlab testing kit. The phosphoric acid was 85% and that’s what I plugged into brun water.

It’s about 5 or 6 weeks since I tested the water, I guess with all the rain it could have changed. I will check it again. It was 20 minutes into the mash when I pulled the wort sample.

sneezles, I added the acid per what brun water said it needed. Without adding it the estimated mash ph was 6.27

I’m not doubting what or how Brun water has their parameters set to, yet, seems ironic to add acid when their is a very dark malt, which brings pH lowering capabilities to the mash, acid. I would almost suggest you do the same brew, leave out the phosphoric acid and verify yer pH… Again to help you see what the variable could be. Marv is very knowledgable, possible a small oops got through his program? Sneezles61

My well water pH is typically 6.9-7.9 depending on the season and rain fall amount. Last time I brewed 5 gals of stout I used 1.8ml of lactic acid. So just because you have dark grains in the bill doesn’t mean you won’t need acid.

Brunwater is the reliable part of the equation here for me. If you put correct values in you will get the predicted result. So for me two things are suspect:

  1. Your water profile. I know nothing about the test kit you used so I can’t say how accurate it might be. I use Ward Labs for my water analysis and test it often with my pH meter prior to brewing. I’d suggest you do the same using well water. I got it tested twice a year for a couple of years and now feel pretty confident in what my meter tells me on brew days. I had it tested last in June 2016 and it’s showing the same pH increase this winter that it did last winter.

  2. The meter. I have a Milwaukee ph55 which I think is a cheaper meter than yours but it does have temperature correction. If yours doesn’t then that could be an issue. The other factor could be the 3 point calibration that @porkchop mentioned. Mine only has 2 point calibration but it’s very reliable and I certainly don’t baby it. It sounds like yours is pretty new. Lots of people use that meter so I’d give it some credibility unless proven otherwise.

So I’d look at those two things. Calibrate your meter to two points, test your water and see if it’s what your test report says. If not you have to suspect the water report at that point IMO.


One other thing be sure you’re using the correct water profile in brunwater. For a black IPA I’d suggest black bitter profile.

Obviously we don’t know what his recipe is but a typical black IPA uses a little carafa to color it. It’s not like he’s got a bunch of roasted malts in there. Besides if his pH is near 8 he’d still need acid to get into mid 5s.

Yeah but even when you take the sample out, you have to let it sit for a little… at least that’s what I understood

I have the same meter, mw102, and although I haven’t looked at the documentation lately I recall it does either an offset (1-point) or slope (2-point) calibration. The 10.0 buffer is for doing a slope calibration for basic solutions.

Read an article today regarding top 10 mistakes using a pH meter. If I can find it I’ll post it. Anyway one thing stood out with regard to this thread. They said when you calibrate you want ot “bracket” your typical readings. So for example most of your readings making beer will be under 7. So you want to calibrate using the 4.0 and 7.0 solutions.

Good info dannyboy. I did calibrate using the 7.0 to 4.0 slope, never said I did a slope on the 10.0 solution. I had just mentioned that since I had some 10.0 solution I went ahead and checked to see if the meter would read it correctly, not by way of calibration just to see if it could read it accurately. It didn’t read it at 10.0, only got to about 9.7

But what you say makes sense about calibrating in a range about where you feel your readings will be. I you find that article please post it.

As for whether brun water or the ph meter was off I may never know and if the beer tastes good should I really care. Does getting into the science of brewing really end up with better beer???

First question I’d say - Nope you shouldn’t.

Second - Yes it definitely does.

Having said that, it’s your beer so just depends on what you want from it and how much effort you’re willing to put into it.

Guess I misunderstood about the pH 10 solution.

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