As the warm days fade and cooler temperatures roll in, it’s time to start thinking about winterising your swimming pool. Whether you’ve had months of summer fun or only dipped in now and then, proper winterisation is key to keeping your pool in good condition through the off-season.
Neglecting to winterise your pool can lead to some nasty surprises come spring, such as cracked pipes, murky water, algae blooms, and damaged equipment. But with a little planning, you can avoid costly repairs and make reopening your pool next season a breeze.
You’ll learn when to start, how to winterise your pool step by step, and what common mistakes to avoid to keep everything in great shape for next season.
When should you winterise your pool?
Timing is everything when it comes to swimming pool winterisation. The general rule is to start when water temperatures drop below 15°C (around 60°F). At this point, algae growth slows down and it’s safe to begin closing up without risking a green pool.
In cooler regions, this might be in early autumn, while in milder climates, you can hold off a little longer. If you’re in a temperate part of Australia, such as Melbourne or Sydney, aim to winterise your pool before the chill really sets in, usually around late April to early May.
Step-by-step guide to winterising your swimming pool
Ready to get started? Follow these simple steps to properly winterise your pool and keep it protected through the colder months.
Step 1: Clean the pool thoroughly
Remove all leaves, debris, and dirt by skimming the surface, brushing the walls, and vacuuming the floor. For a more efficient clean, consider using a robot pool cleaner. These handy devices help keep your pool spotless with minimal effort.
Leaving debris or dirt in your pool over winter can cause staining and disrupt your water chemistry, so clean now to save yourself a headache later.
Step 2: Balance the water chemistry
Before adding any swimming pool winteriser products, test and balance your water. Here’s what to check:
| Parameter | Ideal Range |
|---|---|
| pH level | 7.2 – 7.6 |
| Alkalinity | 80 – 120 ppm |
| Calcium hardness | 180 – 220 ppm |
| Free chlorine | 1 – 3 ppm |
Balancing your pool water helps protect your surface, liner, and equipment over the winter period.
Here’s a helpful tip: add a winter algaecide (or long-life algaecide) to prevent algae growth while your pool is out of use.
Step 3: Lower the water level
Depending on your pool type, lower the water level below the skimmer or tile line. For vinyl-lined pools, lower the water just below the skimmer to avoid pulling the liner.
For concrete or fibreglass pools, aim to lower the level about 10 to 15 centimetres below the skimmer. This step helps prevent freeze damage, especially to skimmers, returns, and tile work.
Step 4: Drain and store pool equipment
Remove and thoroughly clean removable equipment such as hoses, pumps, heaters, and filters. For filters, consider giving them a good rinse or backwash to clear out grime and impurities from summer use. If you live in a freezing climate, blow out plumbing lines with a wet/dry vacuum or air compressor, then plug them to prevent water re-entry and freeze damage. Even though the pool is closed, running your pump for a reduced amount of time during winter can help prevent algae build-up and keep your water clearer.
Step 5: Add winterising chemicals
Give your pool a shock treatment before closing to kill any lingering bacteria or algae. Consider adding a clarifier to help fine debris settle to the bottom for easier cleaning next season. For pools using chlorine tablets, place them in a floater to maintain chlorine levels throughout winter. Remember to adjust the amount of chlorine or salt chlorinator output to suit the lower bather load and cooler temperatures..
Step 6: Cover the pool
Investing in a good-quality pool cover is essential to protect your water and keep out debris. Solid covers block all light, which helps reduce algae growth, while mesh covers allow water to pass through but prevent larger debris from entering. Safety covers are a great choice if you have children or pets, providing extra protection.
Make sure to secure your cover with water bags, weights, or a tensioning system to prevent it from shifting in high winds, and always check for any tears or signs of wear before putting the cover on.
Step 7: Maintenance during winter
Although your pool is not in regular use, it’s important to check it periodically throughout the winter months. Inspect your pool cover every few weeks for tears or debris, and remove any water or leaves that have accumulated on top. Test your water monthly to ensure pH and chlorine levels remain within the recommended ranges, topping up with chemicals as needed. If you have a saltwater pool, keep an eye on chlorine levels carefully, as chlorine can build up under the pool cover.
Extra tips for in-ground vs. above-ground pools
If you’re winterising an above-ground pool, a few extra steps can make a big difference. Using an air pillow beneath the cover helps absorb ice expansion, reducing pressure on the pool walls. It’s important to tie the cover down tightly and check it regularly for any sagging or damage.
For in-ground pools, ensure that return lines, skimmers, and other fittings are securely plugged and sealed to prevent freeze damage during the colder months.
Common mistakes to avoid
Even experienced pool owners sometimes get it wrong. Here are a few mistakes to steer clear of when winterising your swimming pool:
- ⚠️ Forgetting to clean the filter before closing
- ⚠️ Leaving pool toys or floaties in the water
- ⚠️ Skipping a final water balance test
- ⚠️ Not checking for calcium build-up in salt chlorinator cells
- ⚠️ Reducing filtration too early (keep it running 4–6 hours a day until closing)
Prepare your pool for an easy, stress-free spring
Winterising your pool may seem like extra work now, but it’s a smart way to protect your investment and avoid costly repairs later. Following the right steps ensures your pool stays in great condition during the off-season and opens smoothly when the warm weather returns.
