Spa sanitizers brominating tablets * Effective and popular means of disinfecting spa and hot tub water * For the first time and whenever the spa is drained or refilled, add 1/2-ounce of sodium bromide for each 100-gallon of water * Standard dosage introduce 3 tablets per 300-gallon of spa water with the use of a floating tablet feeder or automatic brominator * Available in 3.5-pound