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Old 09-03-2009, 05:36 PM   #1
greenbirds
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Default CaCO3 vs NaHCO3 to increase residual alkalinity - tradeoffs?

So I have a conundrum. I use Palmer's spreadsheet to adjust my (somewhat soft) water. When mashing dark beers I need to up the residual alkalinity to avoid having the pH drop too low.

The problem is that adding CaCO3 seems to be about 3 times less effective on a per gram basis at increasing residual alkalinity as NaHCO3. To get the residual alkalinity up to ~200 ppm, I must add 15 grams of CaCO3, and my calcium levels are through the roof at 400+ ppm (I assume this is bad). If I use NaHCO3, it only takes about 5 grams, but the Sodium level is creeping upwards of 100.

So which route is the lesser evil?

My base water profile from Ward Labs is as follows (ppm):
Ca - 31
Mg - 19
Na - 12
SO4 - 32
Cl - 29
Hardness as CaCO3 - 157
CO3 - 3
HCO3 - 37
CaCO3 - 36
pH - 8.7

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Old 09-03-2009, 10:22 PM   #2
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I'd go with the calcium salt or at least mix them to keep the Na+ level to a reasonable number. I don't understand why some of the common publications recommend baking soda. Sodium isn't a brewing requirement and it is too easy to get a high Na+ count using sodium salt. For my money calcium carbonate is a much better choice. Are you sure about that 400+ ppm number on the Ca+? I'd be less concerned with a high Ca+ than a high Na+. In any event I would bet that you could brew a very good dark beer with a smaller addition, maybe 8-10g. Don't over think it and don't become a slave to ppm numbers in water calculation programs.

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Old 09-04-2009, 12:52 PM   #3
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What is your mash water volume? I plugged in your numbers and got an SRM range of 15-20 SRM just from your source water. Then I entered 5 gal. mash volume and it only took 5g of CaCO3 to reach an RA of 178 and in my limited experience that's plenty. It seems I never need to go to the 'extremes' that the Palmer spreadsheet suggests. Now I just go about halfway there (whether I'm going up or down) and my mash pH is still good.

My water has almost no sodium so I have used a tiny Sodium Bicarbonate addition in addition to CaCO3 additions. But with your sodium content I'd prob just use CaCO3.

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Old 09-04-2009, 02:28 PM   #4
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The reason you have to add so much CaCO3 is because it has very poor solubility. 100ppm Na is not too bad, depending on the beer. You could always add NaHCO3 until you hit around 75ppm Na and then make up the rest of the alkalinity with CaCO3, that should keep every thing in a reasonable range.

In either case, add enough as CaC03 (or other source of Ca) to get your Ca up to at least 50ppm.

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Old 09-04-2009, 03:18 PM   #5
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Quote:
Originally Posted by SpanishCastleAle View Post
What is your mash water volume? I plugged in your numbers and got an SRM range of 15-20 SRM just from your source water. Then I entered 5 gal. mash volume and it only took 5g of CaCO3 to reach an RA of 178 and in my limited experience that's plenty. It seems I never need to go to the 'extremes' that the Palmer spreadsheet suggests. Now I just go about halfway there (whether I'm going up or down) and my mash pH is still good.

My water has almost no sodium so I have used a tiny Sodium Bicarbonate addition in addition to CaCO3 additions. But with your sodium content I'd prob just use CaCO3.
I think you plugged in my "Hardness as CaCO3" value for the "Alkalinity as CaCO3" value on Palmer's sheet. That gave me 15-20 as well. If you use the CaCO3 value of 36 ppm, my SRM is 5-10.

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Originally Posted by Beerrific View Post
The reason you have to add so much CaCO3 is because it has very poor solubility. 100ppm Na is not too bad, depending on the beer. You could always add NaHCO3 until you hit around 75ppm Na and then make up the rest of the alkalinity with CaCO3, that should keep every thing in a reasonable range.

In either case, add enough as CaC03 (or other source of Ca) to get your Ca up to at least 50ppm.
This makes some sense. I thought with mash acidity the CaCO3 would dissolve completely, but if it does not, I assume the spreadsheet is taking this limited solubility into account, telling me to add more.

My thinking is, if I go the NaHCO3 + CaCO3 route, it will be when I have a very dark beer (porter, stout, in this case RIS) that I need to balance. Since I don't care so much about sulfate levels (not going for hop bitterness here), the elevated sodium levels should not create a harsh bitterness since sulfate levels are relatively low. Does this sound reasonable?

And BigEd, you're right. I need to RDWHAHB. This has just been bothering me for a while.
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Old 09-04-2009, 04:30 PM   #6
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You are correct greenbirds, my mistake and my apologies.

I believe you are correct about the Na not being as much of a problem as long as SO4 is kept low. London water allegedly has a decent amount of Na (86 ppm per Palmer).

CaCO3 won't dissolve very well at all unless it's in the mash and then it will fairly easily but I've never added anywhere near the levels your water requires.

I guess the bright side is that you have great water for light brews...well 'bright' only if you like light colored brews.

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