Pools and spas have the potential to become host to a plague of algae, and other bacteria, unwanted impurities and organic life matter. Chlorine is used to sanitise the water, helping to keep it clean and safe for bathers. During this process, chlorine levels can be broken down by the sunlight, combine with the impurities and deteriorate, reducing the ‘free’ chlorine level that it actively available to continue to sanitise the water. This is where shock comes in.
Shock treatments work by applying a dose of high strength chlorine once a week or as and when a boost in sanitisation is required. This causes the chlorine levels to quickly become effective.
It is wise to apply chlorine shock doses to a pool in the end of the day, so that chlorine can work unhindered by sunlight. It is also advised to apply chlorine shock after heavy rain, if your pool has had a lot of use, and especially when you first spot signs algae creeping in. Chlorine shock is also sometimes a useful fix for dealing with cloudy water. Applying chlorine shock should become a part of your regular pool maintenance checklist.
WARNING: Chlorine levels after a shock dosing (sometimes called 'super-chlorination') are extremely high and as such bathing should not be allowed until the chlorine has returned to safe levels, as indicated on your test strips. After any dosing of any chemicals, please always test prior to bathing.