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A little care in autumn saves a lot of work in spring
As the evenings draw in and the leaves start to fall, most outdoor pools in the UK get ready for a rest. It’s a slightly sad moment. But winterising your pool properly has a big effect on how it looks when you wake it up again.
A pool that’s closed properly comes back in spring with clear, healthy water and equipment that’s ready to go. A pool that’s left to fend for itself can turn green, stain, and in the worst cases suffer frost damage to pipes and equipment.
The good news is that the job isn’t complicated. It takes a bit of time and a sensible checklist. In this guide we’ll explain when to do it, what each step involves and why it matters.
If you’d rather not do it yourself, that’s fine too. Talk to us about having your pool looked after as part of your servicing.
Knowing when to start winterising your pool
Timing matters. Close too early and you miss the last warm days. Leave it too late and you risk an early frost catching you out, or algae taking hold in the cooling water.
A good rule of thumb is to start when the water temperature drops and stays below about 10°C. At that point algae grows much more slowly and swimming is only for the brave. In most of the UK this tends to happen around late October or November, though it varies from year to year.
Watch the weather, not just the calendar
Every autumn is different. A mild spell can keep the water warm well into November. A sudden cold snap can arrive in October. Some years the leaves come down early and heavily, and it makes sense to get the cover on sooner just to keep them out. Keep an eye on the forecast and your pool thermometer, and plan to close up before the first hard frost.
Some pools don’t close at all
It’s worth saying that not every pool needs a full shutdown. Some owners with good heating and a quality cover keep swimming well into the colder months. Others leave the pump running on a reduced schedule so the water keeps moving and stays protected from frost. We’ll talk more about that option later on.
Clean the pool thoroughly before anything else
Start with a really good clean. Anything left in the pool will sit there for months, and organic matter like leaves breaks down and can stain the surface. It also feeds algae and uses up your chemicals.
Work through these jobs:
- Skim the surface to remove leaves, insects and floating debris
- Brush the walls, floor and steps to loosen any dirt or early algae
- Vacuum the floor to lift out everything that’s settled
- Empty the skimmer baskets and the pump strainer basket
- Clean or backwash the filter so it starts the winter fresh
Take out accessories and store them safely
Remove anything that doesn’t need to be in the pool over winter. That means ladders, handrails if they’re designed to come out, floats, toys and cleaning tools. Rinse them in clean water, let them dry and store them indoors.
This protects them from frost and sun damage. It also stops them rubbing against your cover or the pool surface during winter storms.
Tidy the area around the pool
Don’t forget the surroundings. Trim back plants that overhang the water, sweep the terrace and clear gutters on any nearby buildings. The fewer leaves that can blow onto the cover, the less work you’ll have over the coming months. It’s a small job that makes the whole season easier.
Balance the water before winterising your pool
Well-balanced water is your pool’s best protection over winter. Water that’s out of balance can become corrosive or start leaving scale on surfaces and equipment. Over several months, that can cause real damage.
Test the water a few days before you plan to close up. Adjust it so that:
- The pH sits in the ideal range of roughly 7.2 to 7.6
- The total alkalinity is where your test kit or service engineer recommends
- The sanitiser level is correct for your system
If your pH has drifted, adjust it in small steps and retest after a few hours of circulation. It’s much easier to nudge it gently than to overshoot and have to correct it back again.
Shock the pool and add a winter treatment
A couple of days before you close, give the pool a shock treatment. This means adding a higher dose of sanitiser to clear out anything lurking in the water. Let the pump run so it mixes in properly, and wait until levels settle back down before you add anything else.
Many owners then add a winter algaecide or a dedicated winterising product. Spread it evenly around the pool with the pump running. This helps stop algae taking hold while the water sits still under the cover.
Stay safe with chemicals
Winter treatments are strong, so take care:
- Always read and follow the label on every product
- Wear gloves and eye protection
- Never mix different chemicals together
- Always add chemical to water, never water to chemical
- Keep swimmers out until the water is balanced again
- Store chemicals somewhere cool and dry, away from children and pets
Our plain English guide to pool chemicals covers what each product does and how to handle it.
Protect your pipes and equipment from frost
Frost is the biggest risk to your pool over winter, and protecting against it is the most important part of winterising your pool. Water expands as it freezes. If it’s trapped inside a pipe, pump, filter or heater, it can crack them. That can mean an expensive repair in spring.
Lower the water level carefully
For a full shutdown, many pools need the water level lowering slightly, usually to just below the skimmer opening. This stops water freezing in the skimmer and the pipes that lead from it.
Please don’t drain your pool completely. An empty pool can be damaged by ground water pressure, and a one-piece shell in particular relies on the weight of water to stay properly in place. If you’re not sure how low to go, ask us first. Every pool is a little different.
Drain the equipment
Once the water level is down, turn off the power to your pool equipment. Then drain any water that’s left inside:
- The pump and its strainer housing
- The filter
- The heater or heat pump, following its own instructions
- Any pipework that can be drained or blown through
Keep drain plugs somewhere safe, such as in the pump basket, so you can find them in spring. If your equipment is in a plant room, check that the room itself is protected from frost.
Or keep things moving through winter
Some owners prefer a lighter approach. They keep the water at normal level and run the pump for a few hours a day, often with a frost protection setting that switches it on automatically when temperatures fall. Moving water is much less likely to freeze.
This is a good option for pools that are well built and properly set up. It also keeps the water in better shape. We can advise which approach suits your pool and equipment best.
Whichever route you take, check the timers and settings before you walk away for the season. A pump that’s meant to run a few hours a day but has been switched off by mistake leaves you without protection just when you need it. If you keep the pump running, keep an eye on the water level too, as it must stay above the skimmer opening so the pump doesn’t run dry.
A good cover finishes the job of winterising your pool
Once the water is balanced and the equipment protected, it’s time to cover up. A winter cover keeps out leaves and dirt, blocks sunlight that algae needs and adds a layer of safety.
Choose a cover that fits your pool snugly and is designed for winter use. Check that it’s secured properly so strong winds can’t lift it. If you have an automatic cover, make sure it’s closed and working well before the weather turns. Our guide to automatic pool covers looks at the different types.
Keep an eye on the cover through winter
A cover isn’t quite a fit and forget job. Check it every few weeks, especially after storms. Clear away leaves before they build up, and remove standing water if it collects on top. Too much weight on a cover can stretch or damage it.
Look for repairs while you’re at it
Autumn is a good time to note anything that needs fixing. Cracked paving, loose coping, a slow leak or a noisy pump are all easier to sort in the quiet months than in the rush of spring. Let us know, and we can arrange a repair before the new season.
Making a quick list as part of winterising your pool also helps you plan. Note anything that looked tired over the summer, from a worn cover strap to a faded light. Come spring, you’ll have a clear picture of what needs attention rather than trying to remember it all at once.
Spas and swim spas need a slightly different plan
If you have a spa or swim spa as well as, or instead of, a pool, winter looks a little different. Most owners keep them running all year. The warm water is part of the pleasure, and a hot soak on a frosty evening is hard to beat.
Keeping a spa running in winter is usually simpler and safer than shutting it down. The water keeps circulating and the heater keeps it well above freezing. The main jobs are:
- Keeping the insulated cover on whenever the spa isn’t in use
- Checking the cover seals well and isn’t waterlogged
- Testing and balancing the water as usual
- Cleaning filters regularly, as they still work hard in winter
If you do need to shut a spa down for a long spell, it has to be fully drained and protected from frost. That’s a job best left to us, so please get in touch before you switch anything off.
Winter pool questions we get asked a lot
When should I close my pool for winter?
Usually when the water stays below about 10°C. In much of the UK that’s late October or November, but watch the weather each year.
Do I need to drain my pool for winter?
No. Please don’t drain it completely. Most pools only need the water lowered slightly below the skimmer, and some stay full with the pump running.
Can I leave the pump running all winter?
Often, yes, especially with a frost protection setting. It keeps the water moving and less likely to freeze. Ask us if you’re unsure whether it suits your setup.
Do I still need to check the pool in winter?
Yes. Check the cover and water level every few weeks, and clear leaves or standing water from the cover.
What happens if I don’t winterise my pool?
You may face green water, stains or frost damage to pipes and equipment. Putting things right in spring usually costs more time and money than a proper closing.
Can HiLife winterise my pool for me?
Talk to us about looking after your pool through the winter as part of your servicing. We’re happy to help.
Making winterising your pool easy
A proper winter routine is one of the kindest things you can do for your pool. Clean it, balance the water, protect the equipment from frost and cover it well. Then check on it now and then until spring.
When the days get longer, you’ll be glad you did. Our guide to getting your pool ready for summer takes you through opening up again. And if you’re dreaming of a new pool for next year, you can explore our full range of pools to see what’s possible.
Call us on 01483 323 676 or email hello@hilifepools.co.uk for a friendly, no-pressure chat, or get in touch online and we’ll come back to you.
