I've been brewing for awhile now using Bru'n Water, RO water and brewing salts to get the right PH. I've been thinminv about using some lactic acid to adjust the mash PH if the predicted PH is off. How do you go about measuring it out? And how do you know how much to add when the mash is under way....example..predicted PH=5.4, Actual PH=5.5. How do you know how much to add? Also at what level are you going to start tasting the lactic?