Maintaining a constant chlorine dose will help kill viruses, bacteria and algae but once a week it is important to boost the chlorine level to help prevent any of these problems occurring. This is known as a 'shock treatment'. You can use one of two chemicals for shock dosing.

1. Calcium Hypochlorite
   Calcium hypochlorite is an unstabilised form of chlorine and is the most common form of shock dosing. As your chlorine source is a stabilised form of chlorine the calcium hypochlorite will help maintain a balance in the stabiliser level. Even if your pool is clean and clear it is still advised that you shock dose your pool once a fortnight or once a week during warmer periods. However if your pool has algae established in it and the water is green then a shock dose is required immediately to clear it.

   It is very difficult to give an exact amount of calcium hypochlorite required to clear a green pool but as a guide:

   • Bottom of 2 metre pool is visible: 500 grams per 10,000 gallons
   • Only 1 metre depth is visible: 1000 grams per 10,000 gallons
   • Can't see the bottom: 2500 grams per 10,000 gallons (Pool A)
   • Pool is a very dark green colour: 5000 grams per 10,000 gallons (Pool B)
   
   

   Pool A

   Pool B

   The required amount of calcium hypochlorite should be dissolved into a bucket of warm water and then poured into your skimmer.

   Please Note: DO NOT MIX WITH ANY STABILISED CHLORINE AS IT WILL EXPLODE!
   Please make sure your skimmer is free from all other types of chlorine before pouring it into the skimmer.

2. Stabilised Chlorine Granules
   Stabilised chlorine granules can be used as a form of shock treatment on smaller pools that are emptied regularly. It is advised that stabilised chlorine granules are used as a shock treatment on above ground liner pools that are only up for the summer season. This keeps things simple and reduces the chances of the pool liner being bleached. They cannot be used on larger in ground pools due to the high cyanuric acid level that will result from using two forms of stabilised chlorine as both your chlorine source and your shock treatment. High levels of cyanuric acid will create 'chlorine lock' resulting in the chlorine becoming ineffective.

Oxy Shock - this is primarily used for spa shock treatment rather than for pools. However if you are maintaining a chlorine free pool then you should use oxy shock - please contact us for advice.