So I have a recipe I got from a brewery in the area for an awesome Hefe. I've just started with tweaking water and have a question about trying to match their water. They use RO water and the recipe says that they add 4:1 Calcium Chloride to Gypsum. I do not have access to RO water. How would I go about adjusting my water to match this, or approximate it.
I carbon block filter it before use.