Gypsum based on Calcium level

[alexlark]

I've got myself a Salifert Alkalinity test kit, haven't used it yet but I'm just trying to get me head around calculating how much gypsum to add to get to the required level of calcium (yes I know I can also add Calcium Chloride, based on Sulfate and Chloride levels).

Say my water has 20 ppm of Calcium and I want to bring this up to 120ppm. I know that Gypsum, per gram, will add 232.4ppm of Calcium per litre.

Now, for a BIAB mash of 30L am I correct in saying that I need an extra 100ppm per litre (3000 / 232.4) 12.91g of Gypsum ?

I know there are tools and calculators out there but I really want to understand the maths behind it.

Thanks, and aleman - your posts are really easy to understand

[Goulders]

Yes

[Aleman]

Looks OK to me :thumb:

[alexlark]

Excellent, thanks for a quick reply. I've "got it" and then "haven't got it" all week. Now I feel I am getting somewhere.

Aleman, based on my example (4g per teaspoon) so just over 3 teaspoons of gypsum. Most of your examples say 1 teaspoon in the mash and 1 in the boil. As I'm doing BIAB and based on 3 teaspoons, would I add half in the mash and half in the boil? This last bit is where I'm a little hazy, I know it all comes down to mash PH.

EDIT: Actually, now I think of it, I require at least 50ppm of Calcium in the mash so, 50ppm - 20ppm = 30ppm, 30 x 30 = 900, 900 / 232.4 = 3.87g

3.87g is roughly 1 teaspoon, so 1 in the mash and the rest in the boil? This sounds right to me!

[Piscator]

Hi Alex - I have been using a calcium kit to verify the sulphate and chloride contributions from gypsum/calcium chloride suggested by the water treatment calculator... since if the calcium ends up where the calculator predicts, it therefore follows that the sulphate and chloride component contributions must as well.
I have found that Grahams water treatment calculator is spot on the money and combined with a proper water analysis has made a significant improvement to my ales.

Cheers
Steve

[alexlark]

Thanks Steve, I ordered a calcium kit yesterday but ideally I should get me water analysed. I'm just dipping my toes into the water treatment side of things after brewing all grain for the last year. I'll take a look at Grahams water treatment calculator, thanks for that.

I've just used the Alkalinity test kit and got a reading of 0.275 meq/L as the syringe read 0.93mls. This makes my water 13.75 CaCO3

[alexlark]

Using Grahams water treatment calculator based on my example in post 2 it says I need to add 12.89g of Gypsum. Can't beat that!


Just another question, the treatment calculator asks for Volume to be Treated, as I BIAB and dunk sparge would I treat the mash water and sparge water separately?

[Aleman]

Aleman, based on my example (4g per teaspoon) so just over 3 teaspoons of gypsum. Most of your examples say 1 teaspoon in the mash and 1 in the boil.

Most of my examples are purely for a I don't really want to get too anal about brewing water, and the tsp in the mash and 1 in the boil pretty much covers it. If you decide that you need to have a better handle than that then it comes down to working out what you prefer, and don't let any calculator, book or website tell you any different!

As I'm doing BIAB and based on 3 teaspoons, would I add half in the mash and half in the boil? This last bit is where I'm a little hazy, I know it all comes down to mash PH.

Full volume BIAB, it all goes into the vessel, job done. If you are doing any sparging, well then it can get a little complicated. Personally I treat everything in the vessel, then I draw off my Sparge liquor and set it aside, job done!

EDIT: Actually, now I think of it, I require at least 50ppm of Calcium in the mash so, 50ppm - 20ppm = 30ppm, 30 x 30 = 900, 900 / 232.4 = 3.87g

3.87g is roughly 1 teaspoon, so 1 in the mash and the rest in the boil? This sounds right to me!

From my last brew I found my mash pH to be a bit high, so I would for BIAB only add everything to the full volume of liquor, or 3/4 to mash and 1/4 to sparge. The extra volume of liquor (and the more dilute liquor to grist ratio) plays around with the effects of water treatment and mash pH, and I haven't yet quite got a handle on it.

[alexlark]

Thanks Aleman, quite informative. That'll do for me

[alexlark]

Aleman, I had the Salifert Calcium test kit back today and my tap water reads 10ppm. I read an old post of yours that says you test your water after adding salts. If I've got all my brewing liquor in a pot and add gypsum, using the calculator, can I go straight ahead and use that water to do a Calcium test? Will it be an accurate test, as far as the Salifert test kit goes?

[Aleman]

I was surprised as to the accuracy of the tests. I sent a sample away to be analysed, and did my own calcium and alkalinity tests . . .I was within 3ppm for alkalinity and 5ppm for calcium (The resolution of the kit) . . . and like you it was towards the lower end of the scale, so even though these kits are designed for seawater with higher levels of calcium they do work at the lower end, using the high resolution test (4ml sample???).

Remember that I usually treat my water the night before, and then draw a sample for testing in the morning just as I start it heating up. so long as the gypsum has dissolved and the water has had a good stir you should be good to go.

[alexlark]

Yes I was surprised how accurate the kits are using water which is so soft.

Up until 2 years ago I had kept marines for a number of years, had a 4 stage RO filter, test kits, TDS meter etc. It's funny how the 2 hobbies cross over. I only kept soft corals so just relied on testing nitrate, phosphate and a few others. I never went full out on water chemistry. I suppose, like you, I just want to improve my beer without getting too concerned over 0.01g of Calcium!

Thanks again

[Aleman]

I love marines but no if I went anywhere near them it would get frighteningly expensive, as I just can't do anything by halves . . . and yes that 0.01g of calcium would be important Even just keeping the planted amazonian tank I have is hard work enough . . . I'm actually having to buy RO water for it as ours has become to unpredictable for Rio Negro 'in flood' conditions now I just keep telling myself I don't have the time or the space to buy my own RO kit, because there is another 800+ quid in gear.

It was keeping fish that helped me understand water treatment, and just what was and, more importantly, was not worth fixating on.

[alexlark]

I love marines but no if I went anywhere near them it would get frighteningly expensive

Yep! That's what happened, freshwater, planted freshwater, marine, reef!!! ... SOLD

When I go to an aquatics centre I could buy it all over again. I kept fish for 17 years so not a bad stint. At the moment Homebrew is cheaper

[Piscator]

Tell me about it! Moving house is no picnic either when you've got to break down a matured, established reef set up and put it back together at the other end - 2 moves later the tank is gone but I do still get the odd twinge of regret. The kit is a lot better and more compact these days but I just know it would eat my time up and I need a time machine to fit everything into a week already. Oddly I was able to transfer some of my water knowledge from marine fishkeeping and brewing to my job in relation to the brining of cheeses!

Cheers
Steve