SilkBalance offers a small, easy to pour 38-ounce bottle that is perfect for a first-time trial. It is designed to last most customers two-three months, depending on how many gallons/liters the hot tub holds and how often it gets used, with an average weekly application of three-four ounces. Once your spa water chemistry is balanced, SilkBalance will maintain your water levels and eliminate the need to buy, store and handle excessive amounts of unnecessary chemicals.