Just wanted to post this as a heads up for anyone who may be trying to use lactic acid to lower their mash pH. There's little info about the actual quantity to use; you want to use a LITTLE. I mean grab your eye dropper little. This stuff is crazy effective, and just a few drops will lower your pH considerably. John Palmer has stated that 2ml/gallon is the upper threshold before it becomes noticeable, which comes to about 1/3 oz. per 5 gallons.