Hard water

[triskelion]

I'm looking for a basic explaination of reducing alkalinity by adding an acid to the water, lactic acid for example. From what I remember from school chemistry, a salt will form in this process. Is there a precipitate that needs to be removed or does it stay dissolved?
My water profile is the following: Ca 64, Mg 4, HCO 86, Na 22, Cl 22, S 110
I'd like to adjust to a very soft profile for lagers. Bru'n water suggests adding lactic acid will reduce calcium and bicarbonate significantly but I'm unfamiliar with doing this. Would it be the total water that is treated or is mash and sparge treated separately?

 

[Yooper]

You definitely want to reduce the alkalinity of the sparge water- so you can treat all of the water at once if you want to, whatever is most convenient for you.

The lactic acid will neutralize the alkalinity. It won't form a precipitant.

 

[Silver_Is_Money]

I presume that where you typed HCO you intended HCO3- (Bicarbonate ion). If this presumption is correct, then your bicarbonate isn't very high, so I will presume your pH to be in the 7's, and therefore your Alkalinity (as CaCO3) to be ~70.5 mg/L (ppm).

Various lactate salts have the potential to form, but likely calcium lactate will predominate. It's solubility is sufficient such that it will remain in solution. You should be well below the threshold of flavor detectability.

Depending upon the style of beer you may want to reduce Alkalinity for both the mash and sparge water at the same time, or you may wish to reduce them separately, such that the mash water retains Alkalinity. This latter case would be of benefit for darker beers.

To reduce Alkalinity whereby to hit pH ~5.4 requires that Alkalinity be reduced by ~90%. (Reduction at the level of 100% will get you into the pH 4.4 region.)

As an example, lets say you want to reduce alkalinity to ~5.4 pH for 30 Liters of your water.

MW of CaCO3 = 100.0869 g./Mole
EQ_Wt of CaCO3 = 100.0869/2 = 50.04345 g/EQ = 50.04345 mg/mEq

70.5 mg/L / 50.04345 mg/mEq = 1.4088 mEq/L Alkalinity

1.4088 mEq/L x 30L = 42.263 mEq of "Total Alkalinity (as CaCO3)"

90% x 42.263 = 38.0395 mEq's of Alkalinity which require removal via acidification

88% Lactic Acid at 5.40 pH has a nominal acid strength of 11.451 mEq/mL

38.0395 mEq / 11.451 mEq/mL = 3.32 mL of 88% Lctic Acid to be added

 

[daveMN]

That water is not that hard. You're in pretty good shape. Bru'n water will tell you to add a couple of ml's for pH adjustment. Adding lactic acid won't reduce your calcium. I have water in the 300 ppm or so range for CO3. I used to preboil to precipitate out the carbonate. That would get me about to your range of carbonate and alkalinity. I've since switched to RO water.

Edit: or, what Silver_is_money more thoroughly and eloquently said at the same time I posted.

 

[triskelion]

Thanks guys. I'd been using some very soft bottled water until now but the shop has stopped selling it unfortunately. I've got a few pale beers planned soon so I'll give the adjusted tap water a shot

 

[Silver_Is_Money]

Does your local water authority add chlorine or chloramines to your tap water?

 

[triskelion]

Here's my water report. I don't see chlorine or chloramines

 

[mabrungard]

That water is only moderately hard. But more importantly, hardness is not always an impediment to good brewing.

As the OP alludes to, it’s actually Alkalinity that demands more attention. Acidification is typically the proper approach for brewing. Only phosphoric acid has the potential to create a precipitate in potable water. All acids neutralize alkalinity by combining the carbonate or bicarbonate in the water with the H protons from the acid. The main concern of acidification, is the addition of the acid’s anion. Some acids can be ‘flavorful’ and that might not be wanted.