Adjusting water after fermentation
I recently brewed an oatmeal stout with fairly soft water.
Chloride 10 ppm
Calcium 13 ppm
Magnesium 4.9 ppm
Sodium 13 ppm
Alkalinity CaCO3 50
Hardness CaCO3 54
Mash efficiency seemed to be fine, what I'm worried about is the harsh taste I've heard associated with brewing darker beers with soft water. Can I adjust after the fact?