Originally posted by twhitehead
They both contain Calcium, Carbon and Oxygen atoms. What other relationships are you looking for?
[b]Did I not make that clear?
No, not really. It is not at all clear what you would like to know. I am sure the Wikipedia pages will tell you about the various properties of both.
They are both white and powdery, but then almost all salts are. (when not in large crystals)[/b]
Ok I'll tell you.
During the process of brewing malted grain is immersed in water. The water is heated to a temperature usually between 64 and 70 Celsius. 66 is considered optimal for enzymatic activity in which the enzymes alpha and beta amylase covert starches into fermentable and not so fermentable sugars. This process of conversion is not only dependent upon temperature but the relative PH of the water, a PH of 5.3 being considered optimal. Now the PH of the water is effected by trace elements, like carbonates. If you live in London you have very hard water because of the presence of calcium carbonate, if you live in Glasgow you have very soft water because of the relative absence of these elements. Not only this but certain types of malted grain also radically effect the PH of the water which is itself directly effected by trace elements. So to reiterate, you have temperature, the types of malted grain and the relative alkalinity of the water which is dependent on trace elements all interplaying to effect the enzymatic process of conversion and its efficiency.
Now here is the crux of the matter. This enzymatic process requires calcium to be present. Calcium sulphate or calcium chloride. The problem with adding these to the water is that they reduce the PH. So if on top of that you have certain types of malted grain like dark malts these also reduce the PH taking it beyond accepted parameters. Therefore to combat this we add calcium carbonate which raises the PH to acceptable levels.
It was this relationship between calcium carbonate and calcium sulphate/chloride that I never understood with regard to how they effect the PH of water in relation to the enzymatic process of converting starches in malted grains to fermentable and not so fermentable sugars. Now I think I understand it.