Mash PH Shockingly below Calculated Target

[Tippsy-Turvy]

My mash pH was 4.9, at room temp!

My mash pH is always +/-0.1 points from the targets derived from Brunwater (worst was +0.2pts) but this was a shocker to me. Being my first darker beer brew in a while and necessitating baking soda, the only explanation I can think of is that the baking soda has degraded with time. Naturally, the pH meter was calibrated.

Does baking soda, kept in an airtight plastic container for about a year, go "off"?

 

[JonM]

What was the rest of the recipe?

 

[The_Bishop]

Which PH meter?

 

[RyGuy77]

Baking soda doesn't really go bad per se. It can lose some of its potency over time depending on environment, but if it is in a sealed container I doubt it has gotten noticeably weaker. You can test it by adding some to vinegar, if you get a reaction it is still good. I think it is more likely that your PH meter was off (I know you said it was calibrated), your measured additions were off, or somewhere in Bru'n water something was entered incorrectly (grains, or water volumes).

 

[RichBenn]

The pH guys hang out in the brew science section. I suggest you try there.. You'll need your beginning water profile, additives, and grains if you want some real help. If you still have all that, there is also a spreadsheet many use there that you can cross check with Bruin water.

Also, check calibration of your meter? Mine needs cal almost every time.

 

[Big Monk]

What malt brand did you use?