Unstabilized chlorine is a form of chlorine added to swimming pools for use as a sanitizer, but does not contain a stabilizing agent such as cyanuric acid, which increases the time chlorine can remain stable in swimming pool water.
What is Unstabilized Chlorine for swimming pools?
Unstabilized chlorine is one of the two forms of chlorine that exist in solid form. Unstabilized chlorine is usually noted as lacking cyanuric acid, as this is the stabilizer of choice for swimming pool chlorine that is stabilized. This kind of chlorine is derived from gaseous chlorine and combined with various chemicals to make a solid since chlorine exists only in gaseous form at normal air pressure. Chlorine is sold as either stabilized or unstabilized form.
With swimming pools, both unstabilized and stabilized chlorine are used interchangeably. Shock treatment products for pools are often unstabilized, as the amount of chlorine added to shock can push cyanuric acid levels higher than desired in the pool water.
With low existing cyanuric acid levels in a swimming pool, stabilized chlorine added to the water cannot be expected to last long, especially in sunlight. It is recommended to shock the pool in the evening, at or near sunset, to avoid unneeded chlorine loss due to ultraviolet (UV) radiation.
- Wikipedia: “Unstabilized Chlorine”, http://en.wikipedia.org/wiki/Chlorine