When mashing, I try to lock my mash pH at 5.2, but always sticks at 6.2-.3 even though I’ve calculated the water profile and added the necessary minerals to reach a 5.2 pH. I’ve gone to the extremes of adding the 5.2 pH stabilizer, but when I check the pH, it reads at 6.0 pH.
The pH meters i’m using are
Milwaukee Instruments MW101
VIVOSUN PH Meter Digital PH Tester Pen for Water
Oakton EcoTestr pH 2+ Pocket pH Meter
I went kinda crazy buying different pH meters thinking maybe the meter didn’t work, but it happens all the time. Also, I calibrate the meter before hand and store them with the storing solution.
My water profile is as follows:
pH - 7.8
Na - 34
K - 4
Mg - 23
CaCO3 - 308
No3-N - 8.4
SO4-S - 23
Ci - 35
CO3 - < 1.0
HCO3 - 256
I will assume the pH meters are calibrated using the calibration solutions.
I don’t see the Calcium, but with that Mg level I estimate it at ~70 ppm.
Dark beers would have a lower pH, you didn’t give the grain bills that you are brewing, but my guess it is usually a lighter colored beer.
Here is a recommendation, try a mini mash, maybe a pint or quart, and use the ratio of water to grain you use. Here is the key part, use distilled or RO water for this to eliminate the alkalinity. If you use one of those water and base malt you should see something like 5.8. Repeat that with some of the minerals to get to your goal and see if you can.
My water is fairly similar to yours, and I don’t brew with it - too much alkalinity.
The 5.2 pH stabilizer doesn’t work, and creates off-flavors. Ditch that and use water software such as Bru’nwater to calculate your acid and salt additions.
If the 5.2 Stabilizer product was all you were using, your results are right where they should be. Five Star needs to update their advertising to read: “Locks your pH at 5.8”. That’s about where the phosphatic salts in the product tend to buffer.
The fairly high alkalinity in your water seems to be overwhelming the buffering power of the 5.2 product, if your readings are 6+. In any case, you are wasting your time with this product. Acid addition is much more appropriate for adjusting mashing pH to 5.4 or less. In addition, acid is needed to neutralize your sparging water alkalinity so that tannin and silicate extraction is less of a problem.