How To Shock Your Swimming Pool

The shock treatment of a swimming pool is for corrective purposes. If your water has lost its transparency and its crystal clean appearance, if it has changed color, tending towards green and if you are concerned that it will get worse in the next 24 hours, shock treatment is the best choice.

This is the last winning option in the face of water that has turned, before considering emptying, even partial, of the pool. Following a non typical event, a shock treatment may be necessary to restore clear and crystalline water.

Given the chemical load implemented by the shock treatment, its recommend shocking the pool at least once every 2 weeks in the middle of summer. 

Basically, it depends above all on the care taken in maintaining your pool and the water it contains. Regardless, if the water begins to cloudy or turn green, don’t wait and act as quickly as possible.

For health reasons, it is not recommended to swim during shock treatment. With the little ones, you must strictly prohibit swimming, explaining why. Depending on how severe the shock treatment is, no swimming for 48 hours is recommended.

Why shock treatment?

If the maintenance and filtration of the pool are properly carried out, then shocking a pool will not need to be done.

The water can then cloud quickly and be overrun with algae in less than 48 hours, taking on a bizarre coloring that is unappealing to swimming and potentially dangerous for your pool.

Faced with this type of inconvenience, the shock treatment is a radical solution that allows you to attain healthy and clean water . Its chemical load eradicates all microorganisms, bacteria, viruses, algae, mosses or fungi that have taken possession of the premises.

When do you need to do shock treatment?

Although this is an exceptional procedure, as the water ages (chemists speak of the age of water), shock treatment will become less rare. Its goal is to use chemicals to find conditions suitable for swimming.

These are the times when a swimming pool will need shock treatment.

  • – After a complete emptying of the pool.
  • – After wintering, when the swimming pool is put back into service.
  • – After a meteorological event: thunderstorm, storm, strong gales, extreme heat.
  • – Following a proliferation or invasion of algae: whatever the reason.
  • – Following a strong use of the pool: a large number of bathers.
  • – Following a bacterial or viral infection of a swimmer to eliminate any risk of contamination.
  • – Before winterizing the pool, at the end of the season. – When put back into service in the spring.
  • – After the first filling

What products should be used to shock your swimming pool.

With a little experience, you will know the right products for you.

If this is the first time or a pool you don’t know, remember that there are no dumb or unnecessary questions. It is better to inquire and ask when you are not sure of what you are doing, whether it is from a specialized store, a forum, a loved one. You’ll save time, money, and less stress about the condition of your pool water.

Chlorine and Bromine shock are the most widely used.

If you usually disinfect your pool with chlorine, use shock chlorine . It is rapidly dissolving chlorine, not stabilized in powder, pellets or granules, based on Calcium Hypochlorite or Sodium Hypochlorite (bleach).

If you usually disinfect your pool with bromine, choose shock bromine .
You can also use shock chlorine (Calcium hypochlorite, Sodium hypochlorite) but you probably won’t.

Active oxygen is the most common alternative.

Pay close attention to incompatibilities between products.

If you are using another form of pool sanitizer, then active oxygen products will often be recommended. Knowing that active oxygen is also very effective in shocking a swimming pool usually treated with chlorine or bromine.

If treating with PHMB, use active oxygen, as it is incompatible with chlorine or bromine.

If treating with copper/silver ionizer or vegetable ceramic, prefer shock chlorine (calcium or sodium hypochlorite) or active oxygen. Do not use shock bromine.

If treating with Ozonator, prefer shock bromine or shock chlorine (calcium or sodium hypochlorite)

If treating with UltraViolets, prefer shock bromine, shock chlorine, or calcium hypochlorite. Do not use active oxygen if and only if the pool is larger than 90m3, the pool is sheltered and the water temperature is over 30 ° C.

How to Start Shock Treatment?

1 – Prepare the pool water.

– Stop all swimming: explain to the little ones if necessary and close access to the pool if possible.
– Uncover the pool: it is probably already uncovered, otherwise, remove the cover or fold up the roller shutter. Shock treatment requires a visual check several times a day. If the inside of the cover or shutter seems dirty, spray them with water.
– Remove the accessories and objects that are in the water: toys, pipes. Clean and rinse them.
– Remove any large debris using a net and empty the baskets of the skimmers and the pump pre-filter.

– (not compulsory) Clean the swimming pool: walls, bottom, water line. If the water is really dirty and you cannot see what you are doing, it is wiser to wait until the treatment has started to act: risk of degrading the coating. Knowing that once the shock treatment is finished, it will be necessary to clean the walls, bottom, waterline, and the submerged parts (skimmers, nozzles, bung, plugs, and various equipment) again. It’s up to you to assess the situation …

– Check the condition of the filter (pressure in particular) and clean it if it seems too dirty to you: washing/rinsing if a sand filter or replacing the cartridge/bag.
– Analysis and adjustment of the water balance according to the shock treatment used, in particular the pH. Also, check the total alkalinity (TAC) and the lime content (TH). Make sure the settings are correct and don’t do anything else until they are: the most important is the pH.

2 – Run the pump continuously until the water has a gray/blue appearance.

– Put the shock treatment products in place. Read the instructions before proceeding. Check that there is no incompatibility.
– Put the filtration in continuous operation.
– Wait for the treatment to take effect by cleaning/replacing the filter if necessary (stop filtration during these phases).

Depending on the state of the water, it can last from 48 hours to a few days. Some water catching can take 2 to 3 weeks.

During this time, you must continue to check the water (pH, disinfectant level) and rinse the filter if it begins to build up pressure (rely on the pressure gauge).

3 – Flocculation and cleaning of the pool to finish.

If the water has become clear again but remains cloudy, use a flocculant or clarifier to conglomerate the residue and remove it more easily through filtration. It may be the remains of dead algae in suspension. Use only if the water has not become clear and crystalline again.

Once finished,
– clean the swimming pool: walls, bottom, water line, submerged parts, using brushes, vacuum cleaner, and/or robot cleaner to find clear water.
– recheck and re-clean the filter if necessary before returning to normal filtration mode.

If you need to, don’t forget that there are companies specializing in pool maintenance. They can intervene occasionally or take charge of the complete maintenance of your swimming pool.