Free available chlorine is the amount of chlorine or sanitiser, left in the pool after dealing with bugs an organic matter already in the water.

Free chlorine kills bugs by a combination of oxidation and complex cell disruption process.

The level of chlorine depends on the type of chlorine you are using. With stabilised chlorine granules, such as Fi-Clor Premium 5 Chlorine Granules, Relax Stabilised Chlorine Granules or Fi-Clor Premium 5 Chlorine Tablets and Relax Stabilised Chlorine Tablets the free chlorine in your pool should always be in the range of 2.0 -4.0 milligrams per litre (mg/l), often expressed as part per million (ppm). With unstabilised chlorine’s such as Fi-Clor Superfast Shock Granules or Relax Granular Shock Granules the free chlorine should be kept between 1.0 – 3.0 mg/l (ppm).

In order to test your pool water you will need to utilise a water testing kit. The most popular type of Chlorine Tester is the Aquachek Test Strips. These test for Chlorine/pH/Total Alkalinity/Cyanuric Acid. They are also available to test for Bromine levels.