Applications: Before Use: Before using this product in your spa or hot tub for the first time, add 1/2 ounce of sodium bromide per 100 gallons of water to establish a 30 ppm bromide concentration. Also, add sodium bromide at this dosage whenever the spa or hot tub is drained and refilled. The bromide addition ensures immediate establishment of an all-bromide system, eliminates chlorinous odors and maximizes skin and eye comfort. Spa or Hot Tub Start-Up: Using a suitable feeder adjusted according to the manufacturer's directions, add this product to maintain an active bromine concentration of 2 to 4 ppm in residential spas and 3 - 6 ppm in commercial spas. Use a reliable test kit to monitor bromine regularly. This product's usage will typically vary from 0.015 to 0.10 pound for every 300 gallons of spa water to maintain the recommended bromine concentration range. The presence of organic debris, high bather use and other factors may require a higher dosage.