Mash water chemistry vs sparge water chemistry

I understand that if I'm brewing a dark beer using soft water I will have to raise the bicarbonate level in the mash water to get the mash to the proper PH range.

I also understand that having a high bicarbonate level in my sparge water may lead to the extraction of tannins as the PH of the mash rises during the sparge. Accordingly, I understand that I should not add bicarbonate to my sparge water as I did with the mash water. Is this correct?

Questions:

- I have read conflicting advice about the relevance of this sparge concern when doing a batch sparge. Is this something to be concerned about or not if I'm doing a 2 part batch sparge?

- What did/do the brewers in places like London do? Did/do they mash with their water straight from the well with its relatively high bicarbonate content but then sparge with water that they treated to reduce bicarbonates? The reason that I ask is that I have been trying to emulate London water for a mild I'm planning (or other city's water depending on what I'm brewing) but I'm now getting the impression that this may not be a good strategy because the water that's good for the mash for a particular beer style may not be right for the sparge because of PH concerns. Needless to say, I'm a bit confused.

MrAverage said:

I understand that if I'm brewing a dark beer using soft water I will have to raise the bicarbonate level in the mash water to get the mash to the proper PH range.

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Probably not. Unless you have made this recipe before, tested your pH, and found that your pH is too low. I would say it's more likely that you will need to acidify the mash than to alkalize it.

MrAverage said:

I also understand that having a high bicarbonate level in my sparge water may lead to the extraction of tannins as the PH of the mash rises during the sparge. Accordingly, I understand that I should not add bicarbonate to my sparge water as I did with the mash water. Is this correct?

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Yes, your sparge should be at or under 5.8 to avoid tannin extraction. You can pre-acidify your sparge water, which is the easiest way, or you can add your sparge as-is, measure the pH, and adjust from there.

I have no idea what brewers did historically, nor do I have any idea if what they made would have been considered "good" by modern standards. I'm sure it got you drunk, though, which is probably all they wanted.

I'm assuming your assumption about needing to add bicarbonate came from one of those RA spreadsheets, like Palmer's. Here is a much better way to go about water adjustments. The spreadsheet also includes a lot of info about water treatment in general.

https://sites.google.com/site/brunwater/

Yes, I should have said that I am using the Bru'n Water spread sheet and that's where my conclusions about needing to add bicarbonate to the mash comes from. The spreadsheet author says that while it's ok to add bicarbonate to the mash, it should not be added to the sparge water because of the PH and tannin concerns - which leads me to belive that the chnistry of the mash water should be differnt from the sparge water...which then led me to wonder what brewers did in the past ...which led to my questions above.

MrAverage said:

- What did/do the brewers in places like London do? Did/do they mash with their water straight from the well with its relatively high bicarbonate content but then sparge with water that they treated to reduce bicarbonates? The reason that I ask is that I have been trying to emulate London water for a mild I'm planning (or other city's water depending on what I'm brewing) but I'm now getting the impression that this may not be a good strategy because the water that's good for the mash for a particular beer style may not be right for the sparge because of PH concerns. Needless to say, I'm a bit confused.

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The did decarbonate by boiling, they do decarbonate by adding CRS (carbonate reducing solution? something like that) which is hydrochloric and sulfuric acid. They would likely treat all of the water the same way.

They probably stopped sparging before the pH got too high. One method of brewing is to assume that you aren't going to sparge more than once. Your efficiency might suffer, but the pH also won't rise as much.

I use hydrochloric acid (muriatic acid), and will be looking for phosphoric acid, to add to my mash and sparge. Still undecided if I want to try treating the water and sparge like normal, or simply accept a small efficiency loss and sparge less. That means more grain and a bigger mash, but less rinsing.

Back in the day, they didn't have pH meters. I would assume that decisions on when to end sparging were based on the taste of the wort runoff. It does become less sweet and more tea-like as the sugars are exhausted.

Bru'n Water does present differing recommendations for mash and sparge water solely on the basis that elevated alkalinity in sparge water is undesirable since it increases the potential to leach tannins due to its ability to increase the mash pH. We acidify sparge water solely to reduce alkalinity. You can hear conflicting information regarding the need to acidify sparge water since there are some water sources that have low alkalinity and would not need acidification for alkalinity reduction. If your water source has more than 50 ppm alkalinity, you definitely need to reduce alkalinity. If your water has less than 20 ppm alkalinity, then you may not really need to acidify.

In the mash, the level of alkalinity desirable in the water will be based on the total acidity provided by the grain bill. There can be cases where more or less alkalinity is needed for the mash water in order to produce a desirable mash pH.