I wanted to share something I found about mash ph with the community. Perhaps it is common knowledge, but to me it was a significant forehead slap.
I’ve been struggling for quite some time with mash ph not matching the ph predicted by brewing software. The difference is as much as 0.3+ in some cases. While this may not affect the finished beer in a significant way, it’s enough of a difference that I have spent time checking equipment and recipes and water alkalinity and acid concentrations and … Basically questioning what I am doing.
A recent experience with an unexpected rise in ph during the boil pointed to one of the additives. That led me to question and check the affect of some mash additives on the ph. What I discovered was for an 8 gallon full volume mash, the ph of the mash water before dough in dropped from 6.4 to 6.0 by the addition of 1/4 tsp of Brewtan-B and 2.5 g of OxBlox. Oxblox contains Brewtan-B is I understand correctly. I knew that Brewtan-B is an acid but never thought that the small amount used in the mash would drop the ph that much.
At any rate I adjusted the amount of acid based on that finding and pretty much hit the predicted value.
If you are using these in the mash, and assuming the brewing software is accurate enough that you don’t need to confirm, beware.
I have also noticed Brewtan B, OxBlox, along with ‘normal’ salts such as CaCl, and Gypsum in combination drops the pH considerably in RO water due to no/low buffering capacity.
MoreBeer states Oxblox 3D has minimal impact on pH but may lower pH levels by 0.2-0.4 in both the mash and the finished beer.
I like the brewing software out there (I’ve used Bru’n water, Beersmith and Brewfather) but I’ve not found any way to account for this in those three. I could have missed it …
Buffer capacity is key. If the water you use has a low residual alkalinity a very slight addition of base or acid can swing the pH quite a lot. Adding a bit of baking soda raises the pH, but it does improve the RA. Read the chapter on water in John Palmer’s How to brew, very informative!
Happy brewing,
Mark van Bommel
I recently brewed another batch using OxBlox and BtB, but this time making sure that the mash water profile had a positive residual alkalinity. That appeared to buffer the affects of the OxBlox and BtB and I hit very near the mash ph calculated by Brewfather. This being a single data point I am going to continue to add some bicarb to my mash water and monitor the ph.
your source water will probably vary on a week to week basis, I work for a brewery and we need different acid additions constantly - only way is to check the pH
That slight variance from brew to brew could be fluctuations in water but also consider we’re using agricultural products that vary from season to season and farm to farm. The software we use was written at a point in time and does great at an initial guesstimate but it can only model an average sample. Actual product used can vary.
I like to give myself some tolerance within the model. Instead of shooting for a specific pH. I’ll plan on being anywhere in the neighborhood: ~5.2-5.4 for Pale, ~5.3-5.5 for Amber/Lite Brown, ~5.4-5.6 for Dark beers.
If I don’t hit the range at my 10 min check, I still adjust mash pH (usually down w/acid) even though by the time I find out the pH the mash is nearly complete. This sets up the pre- and post-boil, fermentation, and finished beer pH.
Interesting observations. I have never used BtB or Oxblox when brewing. I only use RO water which has a pH of 7.5-8.0 from the place I get it and adjust the the pH of the mash liquor with 75% Phosphoric Acid to get it to the 5.2-5.4 range. I then add my water salts and grain and I normally hit the pH to within a few hundredths of the number predicted by Bru’n Water. I acidify my sparge liquor inn the same manner. It only takes about 5 drops or so in around 8 gallons of water to bring the pH from around 8 down to the desired range
I too was off by about 0.3 to 0.4 for a while but found that my pH probe needed to be replaced. that fixed the problem.
That is a good way to do it as well. I just started using this method when the RO water I was getting from the water softener store seemed a bit high (around 8 or so). I was trying to get it to pH neutral but could never hit my target pH in the mash until I adjusted the water before putting in the minerals and it has worked for me. Different strokes for different folks, I guess.
Point taken, I expect some variability. Based on what little I know I assumed that a difference of 0.3 was significantly off target ph. I pretty much always use distilled with salt additions for mash water, but haven’t previously paid any attention to RA. To that point hitting the target mash ph has always been a bit of a crap shoot for me and I’m hopeful that paying attention to the RA will settle this down some.
