Why is my Mash pH so High?

I’ve become a believer that mash pH probably matters for healthy fermentation, hop expression, and even clarity of beer. However, the learning curve is high, it takes extra equipment, and makes brewday a bit more eventful. Because I was given a very expensive pH meter for free, I felt compelled to at least give mash pH a try. I didn’t want to mess with water reports, or add specific brewing salts based on my water, or getting BeerSmith, so instead I focused on using phosphoric to get the mash water pH down to the proper range (5.2 to 5.5, I believe), and that’s pretty much it.


Several batches later, I cannot get the damn pH low enough, no matter how much acid I dump in the damn thing. For one IPA, for example, I added 11 tablespoons of phosphoric acid (10%)  into the mash water. And still had a pH of 5.55! That’s half a bottle, costing $4.50 per bottle. Dark beers are the same thing.

If you do brew in a bag, and begin with the full volume of water (8-10 gallons, say), this is something to consider. You will have to add much more acid to the mash than the traditional method. Further, if your tap water has a lot of “temporary hardness” (don’t ask me to explain), then you will have to add a lot of acid to get through it. Alternatively, you could use RO water from the store.

Acid malt is another option, but I think I would have to add at least two pounds, which is roughly the same cost as acid in the first place.

Next brew I plan on really dialing in the mash pH for an IPA. Stay tuned.

3 thoughts on “Why is my Mash pH so High?

  1. Clive says:

    Thanks for blogging Matt – I’m enjoying reading your posts and will indeed stay tuned! I’ve recently started using salts in my BIAB mash using a water report and Brewer’s Friend online tool to determine what to add and to my surprise they’ve made a great difference to my ales. Yet to measure mash pH though.

    Liked by 1 person

  2. David says:

    Hi Matt. I just discovered your blog. Very enjoyable, as I also only BiaB. I just started exploring water myself, and I’m about in the same place as you in my learning. I do have a water report, and currently use Bru’n Water to guesstimate my pH. I’m waiting on tap space to taste the effects. I have had to use more acid than recommended to get my pH in line, but I believe I’m still under the taste threshold. I look forward to your update!

    Liked by 1 person

    • Thanks a lot David. Well I’m happy to report success. I made an IPA last night and nailed the mash pH at 5.35 with 13 tablespoons of phosphoric acid. I’m very excited to see if there’s a different in quality/aroma/flavor. Proper pH is supposed to improve mash conversion, hop expression, fermentation health, even clarity of the beer.


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