Gypsum

[Pozzi]

I want to use distilled water for my next batch so I used brew father to calculate the mineral/salt additions for the mash. The only problem I am having is which version of calcium sulphate I should buy?

Calcium sulphate dihydrate or calcium sulphate anhydrous? Or will either work?

 

[Yooper]

I want to use distilled water for my next batch so I used brew father to calculate the mineral/salt additions for the mash. The only problem I am having is which version of calcium sulphate I should buy?

Calcium sulphate dihydrate or calcium sulphate anhydrous? Or will either work?

I've never seen dihydrate or anhydrous gypsum. I've seen that with calcium chloride. But if you do see it, you'd want the dihydrate (food safe) form.

 

[Vale71]

Anhydrous is only used in labs and would be wasted as a food additive. The food industry uses the dihydrate form which is commonly known as gypsum and can be had dirt cheap. Since you're going to dump them into a ton of water either form will work just the same, you just have to adjust the dosage calculations to account for the hydration water. All water calculators already take that into account.

 

[Pozzi]

I've never seen dihydrate or anhydrous gypsum. I've seen that with calcium chloride. But if you do see it, you'd want the dihydrate (food safe) form.

Unfortunately I don't have access to a home brew store in this part of the world, but I have managed to find a food grade calcium sulphate, so I'm guessing it will be the right version.

 

[Pozzi]

Anhydrous is only used in labs and would be wasted as a food additive. The food industry uses the dihydrate form which is commonly known as gypsum and can be had dirt cheap. Since you're going to dump them into a ton of water either form will work just the same, you just have to adjust the dosage calculations to account for the hydration water. All water calculators already take that into account.

Thanks! So I'm guessing the one I found is the dihydrate version.

 

[Silver_Is_Money]

Gypsum is the dihydrate form. Molecular weight: 172.17116 g/mol. Calcium's molecular weight is 40.078 g/mol, so the calcium ion is 23.278% of the weight of Gypsum.

1 gram of gypsum added to 1 liter of DI water therefore delivers:

1 g x 1000 = 1,000 mg CaSO4.2H2O
1000 mg x 40.078/172.17116 = 232.78 mg of Ca++ (the ion of calcium)

232.78 mg / 1L = 232.78 mg/L (~ppm) Ca++

When 1 gram is added to 1 US gallon of water this becomes:

232.78 mg / 3.7854 L/Gal = 61.4942 mg/L (~ppm) Ca++ for the case of 1 gram added to 1 US gallon of water.

Note that ppm is only an approximation (or ~) of mg/L since mg/L is a weight divided by volume measure, and ppm is a weight divided by weight measure.