COVID-19 Update

Seasonal Maintenance


When closing down your outdoor swimming pool for winter you need to create a sterile environment where micro-organisms such as algae spores, fungi and bacteria cannot flourish.

You also need to help prevent the formation of scale and staining from dissolved minerals so the water and pool surfaces are in good order when the pool is re-opened in spring. Here is a summary of the things you need to do - for more detailed instructions download the leaflet 'How to Winterise your Outdoor Swimming Pool' or visit Fi-Clor TV to watch a step by step guide.

  1. Thoroughly backwash the filter. Remove any debris from the pump strainer, skimmers and pool water surface.
  2. Check the pH and adjust to 7.0 - 7.4.
  3. Shock dose with a stabiliser-free chlorine such as Fi-Clor Superfast Granules to kill any algae and harmful organisms that may be present. Allow the water to circulate for 3 - 4 hours to ensure thorough mixing.
  4. Close the valve/s from the skimmer/s and lower the water to 10cm - 15cm below the skimmer level. (It is important to heed any recommendations made by the pool installer and not lower the water level too much. This is especially important if there is a naturally high water table as this could present structural hazards to the pool shell).
  5. With the water still circulating through the bottom drain, add the Fi-Clor Winteriser or Multi-Functional Algicide, pouring it evenly around the pool at the prescribed dose.
  6. Leave the circulation running for long enough to ensure thorough mixing.
  7. Remove ladders, diving boards and summer covers etc, and store them away from extremes of temperature.
  8. Switch off and isolate electricity supply.
  9. Drain the water from the pump, heater and filter taking care to retain any 'O' rings from unions.
  10. Disconnect the pump and store in a frost-free, dry place away from extremes of temperature.
  11. Leave valves above water level open; those below should be closed and protected from frost damage.
  12. Some weighted and sealed polythene bottles can be used to absorb ice expansion. These should be floated along the length of the pool and secured with strong cord.
  13. Cover the pool with a heavy duty winter pool cover.
  14. Check the pH and free chlorine occasionally while the pool is shut down. If the winter is mild, add another dose of Winteriser or Multi-Functional Algicide in February.


Getting your pool up and running for the new season is not too difficult, and the following guidelines should make life even easier for you.

For more detailed instructions download the leaflet 'How to Open up your pool in the Spring'. However, if you've got doubts that this particular line in DIY is not for you, give your local Fi-Clor pool centre or service engineer a call.

First, shock dose the pool with Fi-Clor Superfast Granules - Shock & Sanitiser, which is an unstabilised granular chlorine that gets to work the moment it is dissolved. The high dose of chlorine will kill off any algae spores and bacteria that might be lurking in liner creases or in the surface of tile grouting. This will give you as near sterile water as possible. Your pool water needs to kept in good condition throughout the spring and summer as the chlorine will soon dissipate. You now need to add Fi-Clor Multi-Functional Algicide. Its special formulation contains a Long Life Algicide, Water Clarifier, and Anti Stain & Scale additives, which prevent the formation of scale and staining from dissolved minerals.

  1. Remove surface water and debris from the winter cover before taking it off, then clean and dry it ready for storage.
  2. Clean any tide marks at the water line using Fi-Clor Tile & Liner Cleaner.
  3. Reconnect the pump if you removed it over winter making sure all electrical connections are free from dampness. Call in an electrician if you are in any doubt about what your are doing.
  4. Open any valves beneath the water line which may have been closed or plugged.
  5. Check there are no obstructions to the drains, the outlets and the pump strainer basket.
  6. If necessary, top up the water level so that it can be drawn in through the skimmer/s.
  7. Prime the pump, turn it on and check that the filter, skimmers and drains are all working. Do not be too concerned if the water from the circulation is discoloured initially. If the water level was too high because of rain over the winter, pump to waste.
  8. Run the filter for several hours, vacuuming out any remaining debris.
  9. Backwash the filter and top up with fresh water.
  10. Prepare the heat retention cover for use, cleaning off any patches of algae or mould.
  11. Check the pH and adjust to 7.0-7.4. Ask your dealer for Fi-Clor pH & Alkalinity Reducer to lower the pH or Fi-Clor pH Increaser to raise the pH.
  12. Dose with Fi-Clor Superfast Granules - Shock & Sanitiser to kill any algae and harmful organisms that may be present. Allow the water to circulate for 3 to 4 hours to ensure thorough mixing.
  13. Then with the water still circulating, add Fi-Clor Multi-Functional Algicide, pouring it near the swimming pool inlet at the prescribed dose.

Remember these are general guidelines and not specific to your own pool. Always follow chemical manufacturer's instructions carefully. If you are in any doubt as to your ability, contact your local Fi-Clor dealer or service engineer to carry out this work for you.

WARNING. Do not mix Fi-Clor Superfast Granules with any other types of chlorinating compounds (even other products in the Fi-Clor range) either in the dry state, or in the skimmer. Fire or explosion may result. If using with other products, dose them into the pool separately.