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How to winterize an above-ground pool in six steps

Above-ground pools have earned their place in backyards from the inner suburbs of Melbourne to the sun-baked blocks of Perth and the family-sized yards of suburban Brisbane. Once the Easter long weekend rolls around and the kids are back at school, many Aussie pool owners start thinking about closing things down for the cooler months. Winter in Australia is nothing like a Canadian freeze, but the drop in temperature, the shorter days and the steady build-up of leaf litter mean that an above-ground pool still needs proper care to make it through the off-season.

The whole job usually takes a Saturday afternoon if you plan it well, and the six-step routine below is the same one that pool shops in Adelaide, Hobart and the Gold Coast walk their customers through every autumn. You don't need to call in a specialist contractor, and most of the gear is the same equipment you already use for regular maintenance. A solid winter prep also protects your investment from the harsh UV exposure and sudden storm damage that can hit a backyard pool harder than many people realise.

Before you pull on the work gloves, gather your testing kit, a submersible pump or your existing filter pump, a garden hose, your usual range of pool chemicals and a cover suited to your pool's size. A leaf rake, a soft brush and a clean bucket are also handy. Having everything within arm's reach keeps the job moving and means you won't be running to Bunnings mid-task for a forgotten fitting or a missing O-ring.

This guide assumes you have a standard steel or resin-sided above-ground pool with a sand filter or cartridge filter, which covers the bulk of the units sold through retailers like Poolwerx, Clark Rubber and the big hardware chains. If your setup is unusual, a quick chat with your local pool shop before you start will save a lot of fiddling on the day.

Test, balance and shock the water

Step one in any winterising routine is to get the water into the best possible shape before you stop using the pool. A weekend before you plan to close everything down, run a full set of tests using a quality test kit or strip. Aim for a pH of around 7.2 to 7.6, total alkalinity between 80 and 120 parts per million, and calcium hardness sitting somewhere between 200 and 400 ppm for most Australian supplies.

If the readings are off, adjust them over a couple of days using the standard dry acid or sodium bicarbonate you already keep on hand. Australian mains water can be quite hard in areas like Adelaide, so a hardness increaser is often needed after a fresh fill. Once the balance is right, give the pool a shock dose of chlorine to burn off any organic matter that has built up through the late-autumn swim season.

Run the filter for at least 24 hours after shocking. Backwash or rinse a sand filter when the pressure gauge climbs, or give a cartridge filter a thorough hose-down. The water should look completely clear and feel soft on the skin before you move on to the next stage. Skim any floating debris and brush the walls and floor one last time so that no leaves or insects get trapped under the cover once it goes on.

Lower the water and drain the equipment

With clean, balanced water in the pool, step two is to drop the level and start shutting down the running gear. Use your filter pump on a waste setting, or hook up a submersible pump and run the water onto the lawn, never down the stormwater drain. Most councils around the country frown on sending chemically treated water into the street, and the grass will actually thank you for the deep drink on a dry autumn day.

Drop the water level roughly 100 to 150 millimetres below the bottom of the skimmer opening. This stops rainwater and wind-blown debris from being pulled into the plumbing and lets the water level rise naturally with winter rain without overflowing the top of the pool. If you live in a high-rainfall pocket such as the east coast of Queensland or the hills behind Coffs Harbour, leave a little more space so a big downpour doesn't flood the deck and wash dirt back into the water.

Now move on to step three and drain the pump, filter, hoses and any heater or chlorinator. Turn the power off at the switch, unplug the unit, and disconnect the hoses. Drain the pump housing by opening the lid and tipping the water out, then loosen the drain plug at the base of the filter tank. For a sand filter, leave the multiport valve in the open or backwash position so any remaining water can escape. Cartridge filters should be removed, hosed clean and stored inside once they are dry to the touch.

Remove, clean and store pool accessories

This is a good moment in step four to deal with everything that is bolted, hung or hooked onto the pool. Pull out the ladder or A-frame steps and give them a fresh water rinse before leaning them against the shed wall. The same goes for the skimmer basket, the return fitting eyeballs, the hose clamps, and any solar blankets or reels that aren't needed over winter.

Larger above-ground pools often have a top ring and uprights that can be left in place through the off-season, but the accessories come off easily. Store smaller items in a labelled bucket or a heavy-duty garbage bag so you can find them again in spring. If your pool is fitted with a salt-water chlorinator, the cell should be removed, cleaned according to the manufacturer's instructions, and stored in a dry spot. Battery-powered robotic cleaners can simply be rinsed, dried and parked in the garage with a full charge.

This is also a smart time to check for any wear and tear you might have been ignoring. Look for rust spots on the wall, perished O-rings on the pump, or cracked hose connectors. Aussie summers are brutal on pool gear, and a small replacement ordered now from your local pool shop will arrive long before you need to open the pool again in October or November.

Add winterising chemicals

Once the equipment is drained and the accessories are out of the way, the water itself still needs a final round of protection in step five. Even though the pool won't be used, bacteria and algae can still develop during the cooler months, especially in the mild winters of Sydney, Perth and the northern rivers of NSW. A winterising chemical kit, which is widely available in Australian pool shops, contains everything you need in one box.

Follow the label directions for the size of your pool. Typically, the kit will include a long-life algaecide, a chlorine-free oxidiser and a stabiliser that protects the residual chlorine from being burnt off by the strong winter sun in the southern states. Pour the algaecide slowly around the edges of the pool while the pump is running briefly to mix it through. After dosing, let the filter run for another four to six hours before switching everything off for the season.

There is a useful checklist to keep handy when you buy your kit, and another for the final close-down day. Pack these into a single tub so you have everything in one spot come spring.

What to keep on the pool shelf for the job:

Fit the cover and lock everything down

The cover is the single most important piece of equipment in step six of any winterising job. A cheap tarp might be tempting, but a purpose-made above-ground pool cover with a proper fastening system will save hours of cleaning when the weather warms up again. Inlet covers that tie under the top rail, or solid winter covers that clip to the wall, both work well depending on your budget and how much leaf litter falls around your yard.

Before you fit the cover, give the water one last visual check and clear any twigs that have drifted in. Lay the cover so it sits evenly with a small amount of slack in the middle, and tighten the straps or cables according to the instructions. If you are in a windy area, such as the western suburbs of Sydney or the coastal strip near Adelaide, add a couple of sandbags or water weights around the edge to stop the cover from billowing. A billowing cover can scratch the wall and pull fittings loose in a single southerly buster.

Finally, walk around the pool and look at the whole setup with fresh eyes. The pump and filter should be dry, capped and stored under cover, the ladder should be out of reach of curious kids, and the cover should be taut and free of gaps. A small amount of standing water on top of the cover is normal and will evaporate, but make sure it cannot drain back into the pool through any opening or through a sagging corner.

A quick reference of the full six-step routine is worth keeping on the inside of the shed door so you don't have to think it through from scratch each autumn.

The closing checklist in summary:

When the wattles start blooming along the east coast and the magpies begin their early morning carolling, the pool will only need a top-up of water, a fresh dose of chemicals and a wipe of the cover before it is ready for another long Aussie summer.

If anything in the guide doesn't quite match your setup, or you would like a hand finding the right cover or chemical kit for your region, the team at Digijam is happy to point you in the right direction. Drop us a line and we can share what works in your local climate, from the tropics up north to the frosty mornings of Tassie.