How To Close Your Swimming Pool

Pool Closing in Australia - The Ultimate Guide

When the swimming season is over, it can be tempting to just put a cover on your pool and worry about cleaning it when spring rolls around. However, proper swimming pool closure can save you lots of time and stress once opening in the spring.

In this article, we will discuss why pool closing is important, how to close your pool properly, and things you should do while your pool is closed.

Why Close A Pool?

Closing a pool properly prevents a host of problems from developing over the winter months, including severe algae infestations and other unsanitary issues.

Taking simple steps to prepare your pool for the coming winter can save you lots of time and hassle upon reopening.

How To Close Your Pool Properly

#1 - Remove All Debris From The Pool

As you begin to close your pool, remove as much debris as possible. This process may include using dip nets or vacuuming the pool if necessary. You should run your filter continuously during this cleaning period to capture as much smaller debris as necessary.

If you have large amounts of small debris in your pool, you may benefit from using a clarifying agent during this final cleaning. We recommend clarifier tablets, which can be placed in your skimmer basket while your pump is running to help your filter remove small pollution more easily.

#2 - Clean The Filter

After you have removed all of the debris from your pool, empty your skimmer basket of any debris or clarifier tablets and thoroughly clean your filter.

You should use the backwash setting on your pump if this is available, and rinse any removable filter cartridges manually.

#3 - Balance Your Water Chemistry

Ensure that your pool’s chemistry falls within the ideal levels for pH and total alkalinity. Ideal pH in a pool ranges from 7.2-7.6, as pH levels outside this range cause chlorine ineffectiveness.

Ideal total alkalinity levels in a pool range from 80-120 parts per million (ppm), and will help you maintain a balanced pH.

You should also have free chlorine levels in your pool that range from 2-4 ppm. Although it is appropriate to lower your free chlorine levels slightly during the off-season, we recommend maintaining an absolute minimum of 2 ppm to avoid any unwanted surprises in the spring.

If you have a saltwater pool, you should turn your saltwater chlorine generator to a slightly lower setting than during the summer months. This should usually be at around 70% capacity, so long as 2 ppm of free chlorine is still maintained.

#4 - Use Winterizing Agents (Algaecides, Phosphate Removers)

Other chemicals you may want to add to your water before closing your pool include winterizer algaecides and phosphate removers. Both of these products work to prevent algae problems from developing.

Winterizer algaecides are especially potent and typically contain copper as an antimicrobial. It is suggested that you use winter-specific algaecides during the off-season, because these products are designed to be effective even with little water circulation.

Although phosphate removers are not technically a winterizing agent, they can be a great way to prevent algae from spreading rapidly while your pool is closed. To see if this makes a good option for your pool, perform a phosphates test.

We recommend using a phosphate remover if your levels are above 0.5ppm, but there is technically no such thing as too little phosphates. Find out more in this article on how phosphate removers compare to algaecides.

#5 - Check Equipment

After adding any appropriate chemicals to your pool, thoroughly check your pool’s equipment for any leaks, loose fittings, or similar issues. Ensure that all parts of your pump and filter unit are functioning properly, and perform a final backwash of your filter if applicable.

If you have a saltwater chlorine generator, ensure that your salt cell is in working condition and does not have too much calcium buildup on the plates. Set your machine to winter mode if available, otherwise manually lower the chlorine production marginally.

#6 - Drain And Cover The Pool

If you live in an area that gets hard frosts, it is recommended that you drain above-ground pools to a slightly lower level than normal so that there is no water present in the plumbing lines. This prevents any damage and busting associated with ice formation.

If you choose not to drain your above-ground pool to this level, plugs and skimmer intake covers are available that can block water from entering your pump system. You can also use pool-specific antifreeze in your pool’s plumbing if you are unable to remove the water for any reason.

In-ground pools typically do not need to be drained in Australia, despite occasional below-freezing temperatures. Because the ground holds heat, a pool that is full of water is likely to withstand freezing, especially if the water is left circulating during the coldest conditions.

You should cover your pool using a sturdy cover that will prevent debris and rainwater from entering your pool. Avoid using covers with any rips or tears, as even the smallest amount of debris entering the water can deplete your chlorine levels and increase phosphate levels.

This will undo all of your hard work!

While Your Pool Is Closed

While your pool is closed, it is mostly low-maintenance. However, there are some small steps you should take to ensure your winterized pool stays clean.

Check Water Chemistry Regularly

We recommend testing your winterized pool’s water chemistry every other week, or every 14 days. You should be checking your pool’s pH and free chlorine levels to ensure that these still fall within the appropriate range, and should also be making adjustments to your water as needed.

Run Filter (If Applicable)

If you did not drain your pool and the plumbing is still full of water, it is recommended that you run your filter for 2-3 hours per day during the winter to keep your water circulated.

If you are forecasted to have a frost, you should run your pump continuously before and during the period of cold conditions to minimise the chances of any freezing occurring in your pool’s water lines.

When running your filter in the winter, don’t forget to check your pool’s skimmer basket on occasion.


Closing your pool for the winter can sound like a hassle, but it’s an effort that is worth the trade off.

In exchange for closing your pool properly, opening your swimming pool quickly in the spring will be a breeze, which is important when everyone is eager to swim again.

Do you have any questions about swimming pool closure in Australia? Get in touch with us in the comments, we’d love to help!

Louis from Pool Advisor


A chemical engineer by trade, Louis is committed to debunking myths in the pool industry by explaining the underlying chemistry and making it accessible to all.