Generally water supplied by water authorities contains chlorine, the amount varies, often dependent upon the water table level and local conditions, however chlorine will be there.
Other organic and inorganic matter is also present in many cases.

 Features and benefits:

• Used to oxidise or “burn up” contaminants and organic material
• Does not contains chlorine 
• Ready to balance and then sanitise
• Recommended when initially starting up your new spa and also for weekly maintenance