Thank you for you very comprehensive answer. I will call the manufacturer to find out if it is anhydrous citric acid or hydrated citric acid. It does not indicate which it is on the bottle. Thank you again for your help.
Thank you for your suggestion. I was planning on making a gallon of 15% citric acid solution using H20. I'm just not sure how much citric acid to add to get a 15% solution. The citric acid is in a dry form that looks like sugar.