How to winterise your swimming pool

Step 1 – Clean your pool - the first step in closing your pool for the winter is to give it a thorough cleaning.

Manually skim off any floating debris, then scrub the surface with your pool brush, paying particular attention to any areas you see buildup algae, or dirt. 

Once you have thoroughly brushed your pool, run the vacuum to get up any loose debris that might have sunk to the bottom.


Step 2 – Test and balance chemicals levels

Make sure your levels are within the recommended ranges or just a little bit higher since they are likely to drop during the cold months of winter.

  • pH: 7.2-7.8
  • Chlorine: 1.0-3.0 ppm
  • Total Alkalinity: 80-140 ppm
  • Calcium hardness: 100 to 300


Even if you don’t normally test all of these levels, it’s important to do so before closing your pool for the winter.

If any of these levels are off, your pool could suffer over the winter from corrosion and algae. 

Step 3 Add winterising chemicals

Here are all the chemicals you will need:

  • Chlorine (tablets granules or liquid)
  • Pool shock (instachlor),
  • pH Buffer (Sodium Bicarbonate - to raise pH levels if necessary)
  • Algaecide (we recommend Pool Kleer algaecide and winteriser)

Shock the pool with Chlorine and/or Instachlor first (24 hours before you plan to close it). 

Then retest the chemical levels to see which chemicals need to be added to bring them within normal ranges.

Follow up with algaecide (Pool Kleer) immediately  before you close your pool. We recommend 250 mls of Pool Kleer for every 4500 litres of pool water.

5 Litres of Crystal Water Pool Kleer algaecide and winteriser buy now

2 Litres of Crystal Water Pool Kleer algaecide and winteriser buy now

Step 4 -Lower the pool water

Step 5 -Remove any equipment in or attached to your pool, such as rails, ladders, or diving boards.

Step 6 Clean the filter - There are three basic types of pool filters: sand filters, D.E. filters and cartridge filters.

Sand and D.E. filters require backwashing—here are the simple steps:

  • 1. Shut off the pump, roll out backwash hose, check waste line for any closed valves.
  • 2. Turn the valve handle to backwash, or slide a push pull valve.
  • 3. Turn on the pump. Water should flow out backwash pipe or hose.
  • 4. Backwash until water runs clear, about 2-3 minutes.
  • 5. Shut off the pump, turn valve back to filter, turn filter back on.

If you have DE filters, you will backwash them as well, using the instructions for sand filters.

Cartridge filters can simply be removed and hosed off, then replaced back in the tank.

Then reduce the running time of your pool filter.

Step 7 – Cover the pool with a suitable pool cover