The content of this page was updated on 8/19/2012.
I've mentioned that I like to reduce the total alkalinity of my brewing water to 1 mEq/L, and then adjust my pre-treated mash water to its target residual alkalinity. The benefits of doing so, instead of separating my mash and sparge water treatments or simply treating all of my water to the target residual alkalinity of the mash water, are threefold:
-It reduces measurement errors because the weights and volumes are larger.
-It reduces the likelihood of excessive tannin extraction during sparging.
-It's more applicable to commercial brewing because most breweries lack the equipment to treat mash and sparge water independently or change the water treatment for each batch.
Removing alkalinity just to add some back in seemed wasteful at first, but I eventually realized that my kitchen faucet is an abundant source of cheap calcium carbonate.
To collect the CaCO3, I poured the dregs of some lime-treated brewing water into a coffee filter and let it dry over the course of a day. My coffee maker did a good job of removing the standing water, and the filter full of calcium carbonate dried nicely on a plate afterward.