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Simple Guide to Preparing Your Pool or Spa for Winter

  • By Andrew Astonville
  • Published 11/11/2011

Now that winter is fast approaching, it’s an important maintenance factor to ‘close’ your pool, spa or hot tub so that no deterioration occurs during the chilly months that you won’t be using it.

It’s important to ‘winterise’ your pool at the right time, since if you do it when it’s still too hot you’ll encourage algae growth, but if you wait until the trees are losing their leaves you’ll be stuck with a big cleanup.

The following guide will explain how to get your pool snug and sound for the winter months.

Why Winterise?

Pool experts will tell you that it’s important to ‘close’ your pool, spa or hot tub for winter to prevent the various components from freezing. This includes the plumbing, equipment and pool structure.

Steps to Take

Component Repairs

You should firstly check that your pool components are working properly, and if not, it’s best to get them fixed before you winterise.

Water Treatment

Ideally, use your test kit to check the water pH levels, alkalinity, etc. one week before you close the pool. The water treatment should be optimal so that no structural damage or bacteria growth occurs during the months it won’t be in use.

You should balance the water’s pH, calcium hardness and total alkalinity. Chemically treat the water with a sanitizer, stabiliser and algaecide. A winterising treatment will ensure that the water doesn’t become corrosive when the temperature drops to the freezing point or below. Add the recommended amount of chemicals either before draining the pool or prior to securing the cover.


Thoroughly vacuum your pool or spa. If your filter doesn’t have a “waste” indicator, vacuum on the “filter” position only.

Reduce Water Level

Closing the valve on the skimmer line, then lower the water level to around 18 inches below the pool’s edge. How far you lower the level will depends on your type of pool, so find this out in the manufacturer’s instructions. Water levels will also vary according to different types of swimming pool covers, so see the specific instructions for these too.

Piping & Valves

While draining the pool water, be sure to blow water out of all piping. To do this in the circulation lines, use a tank vacuum cleaner on reverse flow or an air compressor. Also try to drain as much water as possible from the heater and filter. Also add nontoxic antifreeze to the piping (this is different from car antifreeze), which can be bought at most pool supply stores and will protect water from freezing to -12° C.

Also thoroughly drain the pool valves. Use an electric heat tape for lines below water level that could be exposed to freezing but can’t be drained or filled with antifreeze.


An easy way to drain the pump is to remove the plugs. Once done, replace the plugs and add ½ – 1 cup or 12 – .24 litres of pool antifreeze solution to the pump housing and then close the pump lid. For cast-iron pumps, coat all drain-hole threads with a suitable lubricant (ask your pool dealer for advice on this) to prevent winter corrosion.


For those of us who live in a cold, northern climate, you’ll need to remove the motor from the pump housing and store it in a warm, dry place. Don’t forget to disconnect the power that leads to the motor before removal.


Using a sand cleaner as the pool water is lowered, backwash the sand filters 3 – 5 times longer than usual (although not while vacuuming). Then, remove the drain plug and open the drain cocks along with the air relief on top of the filter. Next, position the multi-port valve to the ‘winter’ setting and ensure the air-relief valve is left open. After winterising the lines and pump, all filters should be completely drained, so leave the drain plugs out. Also apply a strong lubricant to the threads to prevent corrosion.


Remove the pool or spa lights if they have less than 18 inches of water above them. Then wrap them in plastic and store in a dry place. A tip if you’re strapped for storage is to put weights on the plastic-wrapped lights and place them at the bottom of the pool, but be sure to remove the fuse or turn off the circuit breaker so that the lights can’t be turned on accidentally.

Accessories & Other Equipment

Remove and clean all sundries like handrails, ladders and diving boards. They should be stored in a cool, dry place.


Last but not least, swimming pool covers need to be tightly secured to effectively keep out debris and help keep the water in good shape until summer.

About the Author: Andrew Astonville is an independent advisor on swimming pool covers.



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