pH estimates from Bru'n Water

I noticed an odd think in Bru'n Water the other day that I don't really understand. I've always just used RA for estimate my mash needs and it has served me well. I don't own a pH meter as I'm reluctant to add all that fuss with calibration, lifespan and so on, given the cost.

But I'm interested in my beer pH right now and I'm trying to understand the estimate that Bru'n water gives. It seems to make pH a linear function of the amount of acid put into the beer (rounding makes it a little hard to tell for sure.) Since pH is a log function, that seems off: it should take ten times the amount of strong acid to reduce a solution from 6 to 5 as it does from 7 to 6. So, if one acidifies for a target mash of 5.4, the chance of accidentally going to 5.1 is much lower than going to 5.7. But of course, there are a bunch of buffers in the mash, so maybe that's not right.

How far should I trust Bru'n water for mash pH? Or should I just stick to RA?

I'm subscribing to this.

Plus if the spreadsheet author sees someone dared to answer, he may jump in and tells us all about it.

C'mon Martin tell us, tell us.

I am by no means a chemistry wiz so I won't comment about log vs linear but I do know that I always end up within 0.1 of Brunwater's predicted pH.

I also expected something far from linear when I began exploring RA, acidification, and resulting mash pH. But the surprising truth is that in the range of pH that we typically target in brewing, the response is linear. The other aspect of the algorithm used in Bru'n Water is that it directly uses RA to account for the acidification effect of hardness in the mash.

I'm hoping your aren't a philosofool and have been using Palmer's suggested RA ranges for brewing. They were proven wildly inappropriate many years ago. But I can understand that some myths are hard to kill...especially on the internet...where they perpetuate ad infinitum.

mabrungard said:

I'm hoping your aren't a philosofool and have been using Palmer's suggested RA ranges for brewing. They were proven wildly inappropriate many years ago. But I can understand that some myths are hard to kill...especially on the internet...where they perpetuate ad infinitum.

Click to expand...

Well, as if happens, I think I've been somewhat accidentally fine. My water was low alkalinity (<50ppm) in spring and summer and I tended to target negative RA for the beer I was brewing then, all fairly pale. Probably my pH was on the high side, but not likely above 5.7, maybe 5.8. Before that, I was probably saved by using a water report from a friend which indicated much higher alkalinity, so actual RA was probably 50-100 lower than calculated; if anything, the inaccurate water report seemed to lead to some tart beers here and there. My beer is pretty good, so I don't think I've been suffering the error too much.