I've read in "Big Book of Brewing" that magnesium should be in brewing water at a minimal level of 10ppm, but have also read online that mashed grains will provide an adequate level of Mg for the sake of yeast health. My source water has a level of Mg at 1ppm, so I'm wondering whether I need to add epsom salt to get the Mg level up to 10ppm or just assume that mashing will give me the Mg necessary? I ask because I've seen posts that epsom salt will create a detectable and disagreeable taste in the resulting beer, which, naturally, I'd like to avoid. Using calculators, it appears I'd have to add 2 - 3 grams of epsom salt for a 5 gallon batch of beer. It seems hard for me to imagine that this level of epsom salt addition would create a problem, but I'd just as soon not find out the hard way I was wrong.