Soft water and porter brewing

[khillian]

Hey HBT,

I have soft water here in San Francisco.
Calcium 5 ppm
Magnesium 1 ppm
Sodium 7 ppm
Chloride 4 ppm
Sulfate 1 ppm
Alkalinity 22 ppm as CaC03
Ph 9.2

I plan to brew a BIAB Porter (6 gallon batch) this weekend, 5 into fermenter.

5# Fawcett Maris Otter 2.7L
2# Flaked Oats
1# Wyermann Munich Malt 6L
1# Dingemans Cara45 47L
8oz Crisp Pale Chocolate 275L
4oz Bairds Chocolat Malt 457L
4oz Bairds Roasted Barley 500L

Putting this into a water calculator with 6 gallons of tap water for the BIAB mash
has me adding
1g Gypsum
5g Cacl
which puts me into the proper mash ph range for the mash, I then top up with water to start my 7.2 gallon boil no sparge.

What I do not understand is why people talk of adding baking soda/lime etc with soft water and dark beers? I can never get my ph to go so low that I need to use either in messing around with water calculators. Do these additions listed above make sense or am I missing something?

 

[brewing_clown]

Such low alkalinity and high pH doesn't seem right. However, I'll defer to the brighter scientific minds in the forum on that.

 

[khillian]

This was from ward labs testing just done a week ago. Their results also closely match the averages listed on the SF public page from 2016 sfwater.org/index.aspx?page=634 which has Alkalinity at 39 and ph at 9.4.

 

[brewing_clown]

I learned something. Thanks.

 

[cire]

Hey HBT,

Putting this into a water calculator with 6 gallons of tap water for the BIAB mash
has me adding
1g Gypsum
5g Cacl
which puts me into the proper mash ph range for the mash, I then top up with water to start my 7.2 gallon boil no sparge.

What I do not understand is why people talk of adding baking soda/lime etc with soft water and dark beers? I can never get my ph to go so low that I need to use either in messing around with water calculators.

Mash pH depends upon not only your grainbill and alkalinity, but also the levels of calcium and magnesium. A typical British profile would call for additions 0f 1g Epsom Salts, 5g gypsum and 12g of calcium chloride. Those would substantially lower mash pH and according require additional alkalinity to create a better balance.

 

[khillian]

Mash pH depends upon not only your grainbill and alkalinity, but also the levels of calcium and magnesium. A typical British profile would call for additions 0f 1g Epsom Salts, 5g gypsum and 12g of calcium chloride. Those would substantially lower mash pH and according require additional alkalinity to create a better balance.

I thought adding so much PH lowering power to the point where you have to add back alkalinity to the mash was a bad idea in general? Why not just add those extra minerals to the boil to make it a British profile?

 

[cire]

I thought adding so much PH lowering power to the point where you have to add back alkalinity to the mash was a bad idea in general? Why not just add those extra minerals to the boil to make it a British profile?

Calcium is the most important and influential mineral in brewing and mash pH is not the be all and end all of the process. The influence of calcium in the mash should not be ignored even when brewing only the palest of lagers with low mineral liquors.

 

[ajdelange]

I have soft water here in San Francisco.
...
Putting this into a water calculator with 6 gallons of tap water for the BIAB mash
has me adding
1g Gypsum
5g Cacl
which puts me into the proper mash ph range for the mash,

I don't know the properties of the malts you are using in any detail but using the properties of similar malts I get an estimate of mash pH of 5.39. That's marginal and some people woild argue too low so...

What I do not understand is why people talk of adding baking soda/lime etc with soft water and dark beers? I can never get my ph to go so low that I need to use either in messing around with water calculators. Do these additions listed above make sense or am I missing something?

... those people would argue, justifyably, that if you accept that you need higher pH you will need some alkali.

Such low alkalinity and high pH doesn't seem right. However, I'll defer to the brighter scientific minds in the forum on that.

Alkalinity and pH are fairly independent. For example, a liter of DI water with 0.1 mmol NaOH in it has pH of 9 and alkalinity 5. This is being seen fairly frequently in water today as utilities are increasing pH (in order to protect their distribution) with NaOH. This, as the example shows, increases pH without changing alkalinity much.

Mash pH depends upon not only your grainbill and alkalinity, but also the levels of calcium and magnesium. A typical British profile would call for additions 0f 1g Epsom Salts, 5g gypsum and 12g of calcium chloride. Those would substantially lower mash pH and according require additional alkalinity to create a better balance.

Calcium and magnesium don't usually cause that much of a pH shift because they usually aren't used at such high levels (there are exceptions, of course). With OP's formulation the probable potential pH shift from Ca++ is 0.06 pH. As he is marginal on pH that counts. Note that he has 4.5 mEq/L Ca++ (hardness of 225). Going to 5g of gypsum and 12 of CaCl2 would increase this level to 12 mEq/L, increase the drop from 0.06 to 0.11 and give a beer with 335 mg/L chloride. Seems awfully high. Also water with a hardness of 600 ppm as CaCO3 would have to be pretty thoroughly decarbonated to prevent precipitation of chalk at this level of hardness.

 

[khillian]

I don't know the properties of the malts you are using in any detail but using the properties of similar malts I get an estimate of mash pH of 5.39. That's marginal and some people woild argue too low so...

... those people would argue, justifyably, that if you accept that you need higher pH you will need some alkali.

Alkalinity and pH are fairly independent. For example, a liter of DI water with 0.1 mmol NaOH in it has pH of 9 and alkalinity 5. This is being seen fairly frequently in water today as utilities are increasing pH (in order to protect their distribution) with NaOH. This, as the example shows, increases pH without changing alkalinity much.

Calcium and magnesium don't usually cause that much of a pH shift because they usually aren't used at such high levels (there are exceptions, of course). With OP's formulation the probable potential pH shift from Ca++ is 0.06 pH. As he is marginal on pH that counts. Note that he has 4.5 mEq/L Ca++ (hardness of 225). Going to 5g of gypsum and 12 of CaCl2 would increase this level to 12 mEq/L, increase the drop from 0.06 to 0.11 and give a beer with 335 mg/L chloride. Seems awfully high. Also water with a hardness of 600 ppm as CaCO3 would have to be pretty thoroughly decarbonated to prevent precipitation of chalk at this level of hardness.

Thanks for this reply, helps put everything into perspective!

 

[mabrungard]

SFO water is pretty much snowmelt, right from the Hetch Hetchy. Great stuff. But it's not well suited for dark beer brewing because of its low alkalinity and the resulting lower than desirable wort pH. It still makes beer, but combining roasty flavor and low pH doesn't usually work well. Adding alkalinity tends to help more brewers make better dark beers.

pH and alkalinity are not really related. Each parameter gives you a rough indication of specific ion species. pH tells you how much H+ ion is in the water and alkalinity tells you how much carbonate-species ion is in the water. Very different. You definitely can have low alkalinity and high pH at the same time.

 

[khillian]

So should I be adding baking soda?

 

[ajdelange]

pH and alkalinity are not really related.

We can't really say that. Water at pH has a minimum alkalinity of 1000*10^(pH - pKw) mEq/L or 50 times that in ppm as CaCO3 with pKw being 14 at 25 °C. Thus, as noted in No. 8 water at pH 9 has a mimimum alkalinity of 1000*10^(9 - 14) = 10^-2 = .01 or 0.5 ppm. Water at pH 10 has a minimum alkalinity of 0.1 mEq or 5 ppm. This isn't much and only a factor when pH becomes rather high which is why we can say that pH and alkalinity are fairly independent of one another. But they are definitely relatied.

pH tells you how much H+ ion is in the water

pH tells you the activity of hydrogen ions in the water and how and the relative concentrations (activites, really) of bicarbonate and carbonate. In brewing this is really only significant when doing precipitation calculations.

alkalinity tells you how much carbonate-species ion is in the water.

Alkalinity tells you how much acid it takes to shift the pH of the sample from its pH to 4.5. This is in the vast majority of cases dependent only on the total ions/molecules containing CO2 but in cases of high pH also depends on the pH itself.

You definitely can have low alkalinity and high pH at the same time.

True but pH and alkalinity are not unrelated.[/QUOTE]

 

[ajdelange]

So should I be adding baking soda?

Quite possibly no but then perhaps you should. It depends on the DI mash pH and buffering of each of the malts you are actually using. With dark beers using multiple malts the spreasheets are at their worst because the specialty malts are so variable. The only real way to get a definitive answer is to make a small test mash without and see if the pH falls lower than you want it to. In that case, test mash again with bicab and based on what you find out add the correct amount, scaled to the full brew size, of course, to the main mash.

 

[khillian]

Got it, really appreciate the level of intellect and discussion here. Thanks AJ and Martin.