Soft Water Treatment Quandry

[simple one]

I thought gypsum was easy, and calcium carbonate was hard to get in to solution?

Reading this with interest. I think I would rather have hard water personally.

[Jim]

I find both difficult. Mind, I haven't tried using hot water.

Next time.

[simple one]

Yeah, I have chatted with a few HBers and been told similar stories of having to whisk it in. I add it to the mash and boil most of the time so can't really tell whether it is truly in solution or not. I used to add it to the HLT, but again it had a white bottom, so couldn't really tell.

[gregorach]

Calcium carbonate is not very soluble in water at all - you need something with a lower pH. That's one that I always mix in with the grist.

[trucker5774]

I have just done a hot water experiment. The gypsum appeared to dissolve but then settled out in a few seconds. I tried some calcium chloride flakes (are these of use) and they dissolved instantly. If the gypsum isn't dissolving, what use is it? Can one be substituted for the other? Are they so different that my mash tun will turn to jelly and the beer to custard. I find my tap water is pretty usable. I appreciate there are ideals and the chemists amongst us will be throwing things at the computer..............but getting real...anyone?

[gregorach]

How much gypsum in how much water? Remember, even with distilled or RO water, you're only looking at 10-15g in 30L.

Both gypsum and calcium chloride add calcium, but if your water is very soft you also need to add sulphate to achieve the right mash pH (gypsum is calcium sulphate) so no, they're not really interchangeable.

[trucker5774]

How much gypsum in how much water? Remember, even with distilled or RO water, you're only looking at 10-15g in 30L.

Both gypsum and calcium chloride add calcium, but if your water is very soft you also need to add sulphate to achieve the right mash pH (gypsum is calcium sulphate) so no, they're not really interchangeable.

I did it with 3g in 2 litres. I have been doing some pretty none scientific additions of gypsum and calcium chloride. If have double the amounts and still my soft water mash is around PH 5.6

So, if these additions are NOT dissolving and we are testing the mash as soon as it has been stirred up with the gypsum and water, hows that work then?

[gregorach]

Well, the solubility of anhydrous calcium sulphate is 0.21g / 100ml (at 20 degrees C), so 3g in 2L (0.15g / 100ml) is going to take some dissolving. The 15g in 25L which I use for my very hardest, palest ales is only 0.05 g /100ml. (Interestingly, whilst looking that up, I found that its solubility decreases with temperature - once you get over about 90 degrees C.)

Calcium chloride isn't going to lower your mash pH.

[gregorach]

This is why most people say that water treatments should be added to the grist, not the water.

[Jim]

.....So, if these additions are NOT dissolving and we are testing the mash as soon as it has been stirred up with the gypsum and water, hows that work then?

Once the grain is mixed with the water, the 'chemical' environment is quite different (more acidic) and the gypsum/calcium sulphate dissolve easily (apparently).

I noticed that when just stirring gypsum into the bulk of the water didn't work (settled on the bottom by the next morning); that's why I switched to my current method (which definitely works - the gypsum does not settle out by the next day).

[trucker5774]

That seem to have explained it. Thanks fellas

[Aleman]

Well, the solubility of anhydrous calcium sulphate is 0.21g / 100ml (at 20 degrees C), so 3g in 2L (0.15g / 100ml) is going to take some dissolving. The 15g in 25L which I use for my very hardest, palest ales is only 0.05 g /100ml. (Interestingly, whilst looking that up, I found that its solubility decreases with temperature - once you get over about 90 degrees C.)

Calcium chloride isn't going to lower your mash pH.

Actually that isn't true, calcium chloride will lower mash pH as it supplies calcium which reacts with the phosphate in the mash (released via the phytin reaction). The calcium phosphate precipitates . . . but leaves behind free H+ ions . . .which causes the mash pH to fall.

Therefore ANY soluble calcium salt added to the mash will cause the pH to fall (apart from slaked lime that is as the H+ reacts with the OH- producing water ).

I will say that I have no issue getting gypsum to dissolve . . . but then I add it to the grist, but even adding it to the liquor there was no problem . . . I don't try and dissolve the whole 21g in 1L of water that just won't work as the solubility of gypsum is around 2950mg/l (falling to 26?? something mg/l with hot water). Interestingly enough those of you with hard water may well have difficulty getting even a moderate amount of gypsum to dissolve as the high levels of calcium already present will affect the solubility of gypsum. Why Jim gets a preciptate with his water though is a bit of a mystery??

Both gypsum and calcium chloride add calcium, but if your water is very soft you also need to add sulphate to achieve the right mash pH (gypsum is calcium sulphate) so no, they're not really interchangeable.

Actually they are, it's not the sulphate or chloride that reduces the pH its the reaction of calcium with phosphate that lowers the mash pH. The sulphate or chloride affects the perception of taste, sulphate increases dryness and the perception of hop bitterness, chloride palate fullness and malty flavours.

Ideally you want to be waiting around 10 minutes for the mash to settle before you start messing with the pH. Czech brewers used to hang around for 30 minutes before measuring and altering mash pH during the old triple decoction phases.

[Jim]

..............Why Jim gets a preciptate with his water though is a bit of a mystery??
......

I used to get that when adding a couple of spoonfuls of gypsum direct to 5 gals in a fermenter and giving it a good stir with a plastic paddle. Now I'm dissolving about the same amount in 6l of water (but obvously using the blender to disperse it into a couple of litres first, then mixing the additional water in the plastic bottles), and it seems to work OK.

[gregorach]

Rock on Tony, I clearly need to study this stuff more!

[Aleman]

Rock on Tony, I clearly need to study this stuff more!

The phytin reaction releases small quantities of phosphoric acid from the malt, the phosphate reacts with calcium to for calcium phosphate (which is insoluble . . . think bone), which precipitates and is filtered by the mash. This leave free hydrogen ions in the mash ( in theory they combine with either the chloride or sulphate, but hydrogen chloride and di hydrogen sulphate are VERY soluble ) so the pH of the mash falls. . . . Unfortunately if you have an excessively high alkalinity the free H+ reacts with the bicarbonate ions to form water and CO2 . . . . and the pH stubbornly stays where it would be.