How do you close an above-ground or in-ground pool for winter?
Short answer: Balance the water first: Hayward suggests pH 7.2-7.8, alkalinity 80-120 ppm, and calcium hardness 180-220 ppm. Shock, then add winter algaecide once chlorine falls to 1-3 ppm. Clean the pool, lower the water to suit your cover, drain the pump, filter, and heater, clear or plug the lines, and fit a tight cover.
What chemical levels should a pool have before closing?
Pump maker Hayward suggests balancing the water during the week you close. Its target ranges:
| Test | Hayward closing range | Club Piscine range |
|---|---|---|
| pH | 7.2-7.8 | 7.4-7.6 |
| Total alkalinity | 80-120 ppm | 80-120 ppm |
| Calcium hardness | 180-220 ppm | not given |
Next, shock the pool following the product label. Hayward says to wait until chlorine drops to 1.0-3.0 ppm before adding winter algaecide. Never add shock and algaecide at the same time.
Chemical safety. Never mix pool chemicals with each other, even in a bucket. Add each product to the pool separately, as its label directs. Do not use household cleaners in the pool. Wear the gloves and eye protection the label calls for. Store chemicals dry, closed, and away from children.
How do I clean the pool before closing?
Brush the walls and vacuum the floor. Hayward says a very dirty or algae-filled pool should be vacuumed to waste. That bypasses the filter and sends debris out the backwash line.
Then remove skimmer baskets, wall fittings, ladders, cleaners, and solar blankets, and store them out of the weather.
How far should I lower the water for winter?
It depends on the pool and the cover. Check your cover maker’s manual first. Some covers need no lowering at all.
| Setup | Suggested level | Source |
|---|---|---|
| In-ground, mesh cover | 12-18 in. below the skimmer | Hayward |
| In-ground, solid floating cover | 3-6 in. below the tile | Hayward |
| Above-ground | 18-20 in. below the skimmer | Club Piscine |
None of these sources suggests draining a pool completely. Ask your pool or liner maker before doing so.
How do I winterize the pump, filter, and heater?
Turn off power at the breaker before working on equipment. Hayward says all water must be drained or blown out so equipment does not freeze and crack. Typical steps:
- Open the drain plugs on the pump, filter, heater, and chlorinator.
- Remove and clean D.E. grids or cartridges.
- Store equipment indoors if you can. If not, blow remaining water out with a shop vacuum or compressor.
- Lubricate the pump lid O-ring and any slide valve O-rings.
For heater plugs and other details, your heater’s own manual takes priority.
Do I need to blow out the lines?
In-ground pools. Hayward says to blow out the lines from the skimmer through the equipment and back to the pool. Then seal each line at the pool with an expansion plug. If you skip blowing out, add pool antifreeze per the package directions.
Above-ground pools. Hayward says to disconnect the hoses to and from the pump and filter, then plug the wall outlets. Club Piscine adds cleaning the hoses and keeping the O-rings in a resealable bag.
What kind of antifreeze goes in pool lines?
Use only antifreeze labeled for pool plumbing, not products meant for other uses. Club Piscine describes a calcium-based antifreeze made for swimming pools, poured into the pipe at the pool coping until pink liquid appears. For above-ground pools it suggests about 1 gallon for pools 21 feet and smaller, and 2 gallons for larger ones. Follow the product label for your system.
Safety cover vs. winter cover: which do I need?
A tight fit matters for any cover, says Hayward. The main types:
| Cover | What it does | Notes |
|---|---|---|
| Mesh safety cover | Anchored; lets rain drain through | Hayward calls it “the most desirable and safer” |
| Solid cover | Blocks water and sunlight | Needs a cover pump or siphon for rain and snowmelt |
| Above-ground winter cover | Fits over the pool wall | Club Piscine says not to let more than about a foot of snow pile above the top edge |
Do not treat a loose winter cover as a safety barrier. Water can pool on top of it. The CPSC recommends layers of protection to keep unsupervised children from water. Its examples include barriers, door alarms, pool covers, and self-closing, self-latching devices on fence gates and doors that lead to the pool. Keep your fence and gate working all winter.
Pump standing water off a solid cover regularly.
Quick answers
When should I close my pool? Hayward does not give a date and suggests a pool professional if you are unsure. A common rule of thumb is closing once water stays cool enough to slow algae growth.
What antifreeze goes in pool lines? Use only antifreeze labeled for pools, following its directions. One retailer describes a calcium-based pink product.
Should I drain my above-ground pool for winter? Usually not fully. One retailer suggests lowering it 18-20 inches below the skimmer.
What pH should a pool be before closing? Hayward suggests 7.2-7.8, with alkalinity at 80-120 ppm.
Is a winter cover a safety cover? Not necessarily. Check the cover’s labeling, and keep a fence and self-latching gate as extra layers of protection.