Gypsum NOT dissolved !

Hi there !

I'm trying to reduce the pH of my water which is 7.3 by adding Gypsum .

Its solubility is 2 g/l at 20C .

I just added 0.3 grams of it to 1.2 liters of water at 21C , but I can see the salt precipitating and not dissolving completely !

I also added 0.5 grams of CaCl2 .

Now , the pH is 6.7 .

Can I accept this pH , as not all of the gypsum is dissolved ?

Hector

hector said:

Hi there !

I'm trying to reduce the pH of my water which is 7.3 by adding Gypsum .

Its solubility is 2 g/l at 20C .

I just added 0.3 grams of it to 1.2 liters of water at 21C , but I can see the salt precipitating and not dissolving completely !

I also added 0.5 grams of CaCl2 .

Now , the pH is 6.7 .

Can I accept this pH , as not all of the gypsum is dissolved ?

Hector

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The pH of the starting water doesn't matter- it's the mash pH that matters.

But still, the CaS04 should dissolve. I add it warmer water, though, as I'm mashing in shortly when I add it. I've never had a problem with it dissolving in water that is 78C.

To begin with the pH of your water has little importance in brewing. Second, adding gyspum and calcium chloride will not, theoretically, change the pH of your water. Both are the salts of a strong base (calcium hydroxide) and strong acids (sulfuric, hydrochloric). But as what you buy from the HBS is not pure (calcium chloride often, for example, contains a fair amount of calcium hydroxide) pH can change when these salts are added - especially the chloride.

One of the reasons for adding these salts is so that there will be calcium to react with malt phosphate in the mash tun. That has the desirable effect of lowering mash pH. The other reason is for the flavor active effects of the sulfate and chloride ions.

Gypsum is not, as you have noted, terribly soluble in water. It can take a lot of stirring to get it completely dissolved. It is more soluble in cold water than hot so don't try heating the water to get it to dissolve.

One of the many uses of old White Labs yeast tubes is mixing in your salts, a little bit of water and shaking. Always dissolves that way for me.

samc said:

One of the many uses of old White Labs yeast tubes is mixing in your salts, a little bit of water and shaking. Always dissolves that way for me.

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That's a great idea! Thanks for that tip. I stir well, and the salts do dissolve just fine but I love the idea of mixing them up in the vial first, and then adding them to be sure.

ajdelange said:

Gypsum is not, as you have noted, terribly soluble in water. It can take a lot of stirring to get it completely dissolved. It is more soluble in cold water than hot so don't try heating the water to get it to dissolve.

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i've heard AJ say this before, so I've started adding salts to the cold strike water as its heating. usually by the time it's at temp everything is dissolved, but it generally takes the entire time with a bit of stirring.

I just dump mine right on top of the mash as i'm doughing in, never a problem. As in I always hit my target ph, so it must be dissolving.


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ajdelange said:

To begin with the pH of your water has little importance in brewing......

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In fact , I'm making a mini mash for the first time and I'm going to test my 2-row pale malt to find out my efficiency . I'm going to reduce the water pH to 6.0 by adding salts and also a little acid and then let the mash work . I'll check the pH during the mash , too .

I'm doing this according to John Palmer's "How to Brew" . I mean , reducing the pH by adding salts . Besides , the ppm of the Ca ion in my water is under the desired range ( 16.5 ppm ) , therefore I'm bringing it up to 98 ppm . But , it didn't dissolve completely . That means I have less than 98 ppm of Ca now , or it will be O.K. at mash temperature ?!

All of the salts which I use for brewing are Food-Grade and product of a famous German Chemical Company .

Assay. of my salts :

(CaSO4.2H2O) --> 98 - 102 %

(CaCl2.2H2O) --> 99 - 103 %

Their solubility are also printed on the container :

CaSO4 --> 2 g/l at 20C

CaCl2 --> 1000 g/l at 20C

Should I do my test and see the results , anyway ?!

Hector

samc said:

One of the many uses of old White Labs yeast tubes is mixing in your salts, a little bit of water and shaking. Always dissolves that way for me.

Click to expand...

You're probably not using much gypsum. Two grams of calcium chloride will easily dissolve in 50 mL of water but 2 grams of gypsum won't. Even so, getting the particles suspended in a small volume of water should make it easier to get it dissolved in the larger volume of the HLT.

I've noted here before that I find it very handy to add the salts to a volume that is an easy multiple of the height of my HLT (1 in my case - I dissolve my salts in 35 mL of water beacause the HLT is filled to 35"). If I need to top off the HLT during the brewing session (and I do) I add 1 cc of the concentrated solution for each inch of water I add to the HLT.

hector said:

In fact , I'm making a mini mash for the first time and I'm going to test my 2-row pale malt to find out my efficiency . I'm going to reduce the water pH to 6.0 by adding salts and also a little acid and then let the mash work . I'll check the pH during the mash , too .

Click to expand...

Making a mini mash is a very good way to establish mash pH and there is some control available via the addition of calcium salts. These react with the phosphate in the malt. The water is only a solvent. You will not be able to reduce the pH of the water to 6 by adding salts unless they contain impurities. The proper approach is to use reasonable amounts of salts to the water and then make the test mash. Or, you could mash in with distilled water and then add the salts to the mash bit by bit checking the pH as you go. This would allow you to work up to the proper amounts of salts gradually but would require careful and thorough mixing and a wait for complete reaction.

hector said:

I'm doing this according to John Palmer's "How to Brew" . I mean , reducing the pH by adding salts .

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Just so we are perfectly clear on this: it is the pH of the mash, not the water, that needs to be adjusted. Water pH has little effect on mash pH. What is important in the water is it's alkalinity.

hector said:

Besides , the ppm of the Ca ion in my water is under the desired range ( 16.5 ppm ) , therefore I'm bringing it up to 98 ppm . But , it didn't dissolve completely . That means I have less than 98 ppm of Ca now , or it will be O.K. at mash temperature ?!

Click to expand...

That approach is fine but it needs to be dissolved and you can get it to dissolve as long as you have less than 2 grams per liter though obviously it will dissolve much faster if you have appreciably less than 2 grams per liter. Your proposed 0.3 gram/1.2 liter will dissolve but you will need to stir it until it does. This may take some time.

hector said:

Should I do my test and see the results , anyway ?!

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Never hurts to do a test. You will, if nothing else, get some practice with the use of the pH meter.

And no, I didn't see #8 until after I had posted #9.

ajdelange said:

Making a mini mash is a very good way to establish mash pH and there is some control available via the addition of calcium salts. These react with the phosphate in the malt.

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I did my mini mash .

The mash pH dropped surprisingly by itself , as you said . But , it took 30 minutes for the pH to come down to below 6.0 . I tried during this time to keep the mash temperature at about 122 F ( Protein rest ) . As the pH reached 5.5 ( at room temp. ) , I kept the mash for another 30 minutes at 122 F and then at 130-140 F for one Hour .

I used 0.78 lb of 2-row pale malt and 1.5 quarts of water per pound of grain . But , I got only 540 ml of mash water ( before sparging ) and at the end I got 0.53 Gallons of wort with the gravity 1.027 .

Would you please tell me how to calculate my Efficiency .

What should I do to get more Volumes of wort ?

Hector

hector said:

What should I do to get more Volumes of wort ?

Hector

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Use more grain. Say you use three pounds of grain. (Skip the protein rest and just do a single infusion mash at 150-152. Mashing low takes longer for conversion and can be another problem you're having).

So, three pounds of grain at 1.5 quarts per pound means a mash of 4.5 quarts (or one gallon is fine). The grain will absorb .125/gallons per pound of grain. So, you'll put it one gallon and get out .625 gallon out of the mash. Then you can sparge up to your boil volume- probably 1.5 gallon more-- so you can end up with about a gallon after your boil.

You can calculate the efficiency approximately by dividing 27 ( = 1000*(1.027 -1) ) by 4 which gives you 6-3/4. Your wort is thus about 6-3/4% extract by weight. You have 0.53 gallons of wort which weigh 0.53*8.34*1.027*0.998203 = 4.53 pounds. 6-3/4% of that is 0.37 pounds of extract. Your efficiency is the amount of extract you got divided by the weight of grain that it took to produce it i.e. 0.37/0.78 = 39.2%. This is pretty low but then this was a test mash that you only took to 140 °F. Given that you got the pH just about right on you should achieve a much higher efficiency in the full mash.

Note that home brewers usually don't compute efficiency this way. They will compare to the maximum efficiency which they take to be the Congress mash value determined in the maltster's lab. This is usually about 80%. They would call your efficiency 39.2/80 = 49% but would arrive at it by comparing the gravity points (27) you got per pound of grain per gallon to an expected points per pound per gallon which you would look up in a book or spreadsheet.

As to volume you got 540 mL of initial runoff and then about 2 L after sparging. That represents a lot of sparging. Usually one sparges to a lot less volume than that and usually determines the amount of water to use by cutting off collection when the runoff gravity gets down to 1.012 - 1.016 or so.

hector said:

I did my mini mash .
Would you please tell me how to calculate my Efficiency .

Hector

Click to expand...

See https://www.homebrewtalk.com/f36/my-efficiency-292618/