Star San is an acid based no rinse sanitizer. Use only one ounce per 5 gallons of water. Star San is odorless, flavorless, and requires only one to two minutes of contact time. This product does tend to foam, which has advantages and disadvantages. The foaming action helps to sanitize cracks and crevices, but you need to allow extra time for draining. The foaming action is perfect for plastic fermenters. You can minimize the foaming effect by adding Star San to the vessel after the water has been added, and by siphoning as opposed to pouring the solution between vessels. Since Star San is acid based, contact with soft metals should be kept to a minimum. Kept in a sealed container, a Star San solution will stay effective for as long as three to four weeks.