How To Shock A Pool
If you are wondering whether or not you have to shock a pool, the answer is yes. Shocking a pool helps to keep the water clear and safe for swimmers. When shock is added to a pool it oxidizes the organic wastes in the water such as bacteria, sweat, oils, urine, leaf litter which have combined with the chlorine in the water to form chloramines (or combined chlorine). Combined chlorine is not as effective as a disinfectant as freely available chlorine.
Both chlorine and non chlorine shock treatments area available. With chlorine shock the most common active ingredient is calcium hypochlorite but dichlor and lithium hypochloride are also used. Non-chlorine shock consist of potassium monopersulfate. While both types are usually compatible with chlorine, ozone and bromine treated pools, spas and hot tubs, always ensure you check this on a product by product basis. None of these products can be used in a biguanide pool. Only concentrated hydrogen peroxide can be used as a shock treatment for these pools.
If you have a vinyl liner or delicate surfaces that may be susceptible to bleaching, a non chlorine product may be a better option although some fast dissolving and liquid chlorine shock treatments have been specially designed to avoid bleaching. Non chlorine products are popular for use in spas and hot tubs. In hard water environments (above 200 ppm) a lithium, non chlorine or liquid pool shock will be a better option than calcium hypochlorite products.
You will need to shock the pool weekly or once every two weeks depending on usage. Determining the quantity of shock treatment to add is dependent on a number of factors:
- The level of combined chlorine in the pool.
- Whether you are using chlorine or non chlorine shock and in what concentrations. For shocking with a chlorine product, you need to add around 10 times the level of combined chlorine. Non chlorine shocks are generally added on a 1 to 1 ratio with each product oxidizing 1 pound of combined chlorine.
- The size of the pool.
- Any specific instructions from the manufacturer. Most products have a pool shock calculator to help with determining dosage amounts.
How To Shock A Pool
- Remove all leaf litter and other debris from the skimmers and filters as these will quickly diminish the pool shock effectiveness.
- Ensure all swimmers are out of the pool. Never allow anyone to enter the pool while chemicals are being added.
- Keep the filtration system running while you shock treat the pool to ensure even distribution with no dead zones.
- Remove all pool accessories, such as floats, from the pool.
- Avoid adding pool shock in windy conditions.
- Try and avoid shock treating during the full sunshine. Many pool users get into a routine of shocking the pool every Sunday evening as this coincides with the end of what is normally the busiest period of pool use.
- Ensure that the product has not expired. The average shelf life for swimming pools shock is around 12 months.
- It is generally a good idea to pre-mix granular shock before treating to ensure that deposits do not remain on the floor. Follow the product instructions.
- Wear gloves when working with pool shock and be careful of splash back when broadcasting over the pool. Goggles are a good idea.
- Once you have opened a package, do not reseal and reuse.
- Continue to broadcast until you reach a stable level of free chlorine.
- Only allow swimmers back in the pool when chlorine and pool chemistry is in a safe range.