Carbonate reduction may be performed in a couple of ways. Carbonate levels can be lowered to the 50-150 ppm range by two methods, boiling or dilution. The problem with boiling is that it can only remove the temporary hardness (which is the lesser of the total alkalinity and CaCO3 or the total hardness as CaCO3).
(In chemistry, Carbonate Formula: a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, CO3-2 but may also mean an ester of carbonic acid, an organic compound containing the carbonate group C(=O)(O–)2. Bicarbonate formula: Bicarbonate is a polyatomic anion with the chemical formula HCO−3. Bicarbonate serves a crucial biochemical role in the physiological pH buffering system). Source: Wikipedia
Another way of performing carbonate reduction involves adding slaked lime or "pickling lime" to the water. The problem with this method is that you must calculate the amount of lime to add carefully, and it must be added gradually while monitoring the pH carefully to avoid creating very alkaline water from excess hydroxide. For those wanting to try this method of carbonate reduction, here is how John Palmer suggests doing it in his book, How To Brew. I'll calculate using my water profile and 10 gallons of water.
Probably the easiest way (after reading the above procedure you can see why) to accomplish carbonate reduction in your brewing water is by dilution with distilled water in a 1:1 ratio. Doing this will effectively cut your carbonate levels in half. Adjust the ratio accordingly. So, if you want to brew a pilsener with hard water, dilution of your hard water with distilled water is the easiest way. For example, if my total hardness as CaCO3 was 80 ppm, and I wanted to lower my carbonate levels to below 50 ppm in 10 gallons of brewing water, I'd have to dilute with 83.33% distilled water. If I try to boil my 10 gallons of brewing water to remove some of the carbonates, I'd only be able to remove approximately 30 ppm, which would get me down to the 50 ppm solubility constant of calcium. That's not much of a reduction for so much work and propane. Dilution is obviously the best way to go in this example.
Reference: Information for this article was taken from John Palmer's book How To Brew.
If you find this site helpful, please link to us!