Treat mash and sparge water or just mash water?

[TandemTails]

I've recently started treating my RO brewing water with calcium chloride and gypsum. I've been adding additions to both my combined mash and sparge water, then divide that into the correct gallons for each respective step.

Since I'm using RO water, I figured treating all of my brewing water is the correct step to take. Is this correct or should I only be treating my mash water?

 

[Epos7]

I BIAB, but if I do a sparge step, I treat both. CaCl and gypsum affect the flavor of the finished beer, so if you didn't treat the sparge water you're just diluting, and should consider your water profile as the diluted solution. I pH adjust my sparge water, too, although I'm not sure if this is as necessary since pH is most important during the mash.

 

[mabrungard]

Be careful! The water chemistry of mashing and sparging water can be different due to the varying acidity of brewing grains. In general, sparging water should always have low alkalinity. However, mashing water might need anything from less than zero alkalinity to modest alkalinity in order to produce a desirable mashing pH.

You don't have to add the minerals directly to your sparging water. You can add them directly to your kettle instead. Just be sure to add an appropriate quantity based on your actual sparging water volume in order to produce your desired water profile.

 

[Jbrown57]

So the additions to the mash water would be the post boil volume plus the estimated water loss due to absorption by the grain?
Sorry just trying to fully understand the process.
jbrown57

 

[mabrungard]

I suggest that using the actual mashing and sparging volumes is sufficient in most cases. The only time you might consider reducing the mineral additions is if your system has high evaporative losses during the boil. Homebrewers should keep their post-boil volume to within 15% of the original pre-boil volume. Most Pro systems limit their evaporative losses to between 6 and 10%. Homebrewers would be wise to do the same.

 

[Jbrown57]

thanks for the clarification.
jbrown