Porter Water Chemistry Question

dmcmillen · Apr 27, 2016

I am getting ready to brew a Robust Porter using Bru'n Water's Brown Malty profile. When I make my water adjustments my final profile is Ca 59.8, Mg 5.3, Na 28, SO4 52.4, Cl 61.4, HCO3 119.7 (RA 53). Bru'n Water estimates a mash pH of 5.5 which is certainly in range.

If I add a bit of Lactic acid I can get the est. pH down to 5.4 but that lowers the bicarbonate down to 83 and the RA to 23.

I understood that for darker beers like porters and stouts that have more acidic malts we need more alkalinity such as bicarbonate (weak base/acid). Also I thought we needed a much higher RA the darker the beer. I have seen posts with folks pushing RA into the 200's for SRM in the 30 range.

Should I be concerned about the the pH of 5.5 or leave it where it is without adding any acid? Should I be trying for a higher RA and if so I'm not sure how I would do that. I know adding chalk and baking soda increase RA but I don't see how I would do that and keep my numbers where I need them.

Appreciate some thoughts here.

McKnuckle · Apr 27, 2016

In my opinion... leave the 5.5 pH alone - it is ideal for a porter or stout. And it's been frequently discussed that you aim to adjust for pH, you don't worry about alkalinity itself as a factor that must match a particular value. The RA is a means to an end - the end being the mash pH.

From a mineral perspective, your profile is nice and reasonable. Ca, SO4, Cl all around 50-60, Mg nominal, and Na present but moderate (it will soften the edges of a roasty beer).

mabrungard · Apr 27, 2016

As properly mentioned above, RA is a means to an end. It should not be a target. Only pH is a target along with the flavor ions.

I'm in the process of recoding the free version of Bru'n Water to remove extraneous items like RA reporting and the SO4/Cl ratio from the program so that brewers will focus on the actual important items they should be. Look for it in the next few weeks.

dmcmillen · Apr 27, 2016

Thanks. Pretty much what I was thinking. Just recalled the posts of people using EZ Water (probably older version) that focused on RA for darker beers.

Martin, I do find the so4/cl ratio useful but that's easy to calculate.

dmcmillen · Apr 27, 2016

Additional comments on RA. I finally remembered the Palmer video (from a training he did) on RA and Brewing Water. In it he talks about a NHC-Denver experiment where they brewed a Pale Ale twice, one with RA water of -50 and one with RA water of 200. Then they brewed a Sweet Stout twice, one with RA water of -50 and one with RA water of 200. Their conclusions were that beers brewed with the "right" RA (low for Pale Ale and high for Stout) were more complex and the beers with the "wrong" RA were more 1 dimensional. His conclusion was to match the RA to the color of the beer style.

ajdelange · Apr 27, 2016

John is, today, much older and wiser than when he was promulgating ideas like that. As Martin implied RA really has very little to do with the formulation of a brew. It was proposed by Kohlbach in 1941 as a way of comparing brewing waters and if you know how to interpret it properly it can give you a rough idea as to what you need to do to brew with a water with a given RA. To properly design a beer using a given water and malts we must zero the proton balance equation at the desired mash pH. RA happens to be the sum of two terms in that equation but it is by no means the whole story no matter how desperately John wanted it to be so at one point in his career (and I did too). We are beyond that now.

Editing because I just read the OP. When trying to brew to match a profile you ignore not only the RA but the bicarbonate. At mash pH any bicarbonate that was in your water will have had to have been neutralized (taken out) and if you are formulating a profile from a spreadsheet do not make any additions of bicarbonate or carbonate in order to match the spreadsheet's profile for this reason. If your water is alkaline the spreadsheet should reflect the need to neutralize that alkalinity through high mash pH predictions unless acid is supplied.

dmcmillen · Apr 28, 2016

AJ & Martin - thanks so much for your continued education here in the forums and helping me and others understand the complexities of the brewing water chemistry. You have helped me immensely. Based on where the science and understanding is today there sure is a lot of "old" mis-information out there to weed through. But I'm having fun. Thanks again.