Water Chemistry Surprise

[Nil]

Hello All,

Based on my latest home brewing experience, I decided to move forward with RO water and get into water chemistry.

Now. All the time I had been said that 1 - 2 tbs of Calcium Chloride Dehydrate will be suitable to adjust the pH of the mash and I have been doing this blindly for a couple of years.

Based on my calculations, 1g of CaCl2 Dehydrate delivers 14.4 ppm of Ca2+ and 25.5 ppm of Cl-.

Since CaCl2 density is 2.15 g/ml and 1 tbs = 15 mL, 1 tbs would deliver 32.3 g of CaCl2. Assuming that I add 2 tbs of CaCl2 to the mash and don't add any to the sparging water, AND I add the same amount of sparging water relative to the mash volume, then the actual amount added would be 1 tbs and not 2 tbs because of dilution.

Yet, 32.3 grams of CaCl2 would deliver 14.4 ppm X 32.3 g = 465.1 ppm of Calcium and 823.7 ppm of Chloride!!!

Please let me know if I am missing something.

Thanks, Nil

 

[Yooper]

Well, let's see. There are about 3.5 grams of CaCl2 in a teaspoon, and 3 teaspoons in a tablespoon so that's about 10 grams.

It's hard to say, because CaCl2 absorbs water from the atmosphere like crazy- it's very hygroscopic. But let's say that's so.

In 5 gallons, 10 grams of CaCl2 would provide 255 ppm of chloride and 145 ppm or so of calcium- too much. Doubling that would be even more, of course.

Using gypsum or calcium chloride to adjust the mash pH is not a good idea- use acid to adjust the mash pH appropriately and use flavoring salts for flavor.

 

[Nil]

I double checked today. My problem was that the 2.15 g/mL is based on a microzined CaCl2. The one that I get spheronized.

Made a weight test and 1 tbs = 14.2 g. As you said, still high yet not as high as I expected.

I don't expect water absorption issues since I stored the pellets in a tied ball jar with 2 desiccants.

With regards the pH adjustment, my RT pH was always around 5.9 (for light to light amber beers). I want it to be 5.6 @ RT in order to have 5.3 @ mashing temperature. So I did not considered an issue using CaCl2. I never used CaSO4 since it is more difficult to dissolve and also can augment bitterness.

Now that I got into RO water, I should be more careful. Any spike on City Water Cl- can mess up the flavor profile of the beer. No really so concern about the Ca2+ since it is consumed by the chemical reaction that lowers the mash pH, use for hot brake during boiling, and by the yeast.

Thanks, Nil

 

[mabrungard]

I need to confirm your terminology. Does 'Dehydrate' mean that your calcium chloride has no water of hydration (which is normally termed: Anhydrate), or are you referring to 'Dihydrate' which means there are two water molecules attached to the calcium chloride?

While the desiccants in the jar should reduce the potential for additional hydration of the calcium chloride, it won't reduce any hydration that the salt has already picked up. One of the better ways to control this hydration issue is to create calcium chloride solution and measuring its specific gravity to know how much calcium chloride is actually in the solution.

 

[Nil]

Sorry, Dihydrate, meaning it has 2 moles of water within the CaCl2 crystal structure.

Why you recommend to measure specific gravity? This is a dimensionless value that is based on a mass ratio at water T = 4 C.

Density would be a better choice (g/mL). Down side is that, for a density measurement, I would required an analytical scale that cost $3000 - $5000.

What I would do is to measure specific gravity and multiply it by 0.997, that is the approx. water density at RT. This would deliver density in g/mL and then I can evaluate the CaCL2 solution content.

Please let me know if I am missing something.

Thanks, Nil

 

[ajdelange]

The easiest place for you to get data on CaCl2 from solution strength is right at the top of this forum at https://www.homebrewtalk.com/showthread.php?t=501377. The strength is given in terms of a simple polynomial in specific gravity but it is 20°C/20°C specific gravity. You can come up with your own polynomial for any other temperature pair you like or for density from this but it seems simplest to just use what's available.

 

[Nil]

Good source. Don't know how the author determined that a SG = 1.0557 = 68.14 g/L.

Anyway, I am under the impression that you a missing a point: the term "dihydrate" to water within the crystal structure of the CaCl2. The extra water from the environment is adsorbed onto the crystal surface. If this is correct, then one can heat the CaCl2 pellets in a microwave to remove these water molecules and then dissolve in distilled water.

Thanks, Nil

 

[Nil]

I got how the author determined that a SG = 1.0557 = 68.14 g/L. Never mind.

 

[ajdelange]

The water forms dative bonds with the calcium ion and one can indeed drive it off by heating in an oven which also drives off any water adsorbed to the surface. To get the last water molecule requires a fairly high temperature - 250 °C I think but that's a guess based on hazy recollection. As soon as it comes out of the oven it has to go straight into a dessicator protected from air. The instant you start to weigh it out it begins picking up moisture.

If you read the sticky you will see that it is possible to have a range of levels of water of hydration in a sample of CaCl2. If you seek an accurate level then dissolving in water and measuring the SG is easier than drying in an oven, then dissolving in water and then measuring the SG. For most brewing applications you can assume 80% by weight of the powder yoy buy is CaCl2. You can also buy pre-prepared solutions of specified strength. These too take up water from the air but to a much lesser extent than the solid (provided they are kept in tightly stoppered bottles).

The author of the sticky found hundreds of data points on density of calcium chloride solutions including data going back to the 1800's, converted to 20/20 SG assuming that most brewers would have 20/20 hydrometers as opposed to density meters and fit a polynomial to the lot.