Every time you drain and refill your hot tub or when starting with Silkbalance water care for the first time, you need to flush and purge the plumbing lines underneath to clean away the organic deposits, sludge and slime build up. This concentrated liquid formula is specially blended to work in less than 30 mins, is a low foam formula and will deep clean the spa pipes, jets and plumbing equipment giving you that truly Clean Start.