How to Winterize Your Above-Ground Pool (Chlorine and Salt Systems) Pool Closing Guide

When the nights get colder and autumn leaves start to fall, it’s time to winterize your pool! As a rule of thumb, begin winter preparations when daytime temperatures are consistently in the mid-60s°F (about 18°C) or lower. Starting too early can invite algae problems, while waiting too long risks freezing damage. Plan on roughly a week to close your pool properly.

1. Deep-Clean Your Pool:

Clean debris and scrub surfaces: Remove all leaves, twigs, and floating debris with a skimmer. Brush the walls and floor thoroughly to loosen dirt and algae. Vacuum the pool to waste (or backwash) until the water is crystal-clear.

Clean skimmers and filters: Empty the skimmer baskets and brush the skimmer walls. Run the filter longer than usual in the days before closing to catch any leftover fine debris. A squeaky-clean pool is easier to balance chemically and helps prevent stains and algae growth during winter.

2. Balance Pool Chemistry for Winter

Balancing the water before closing is critical. Use a reliable test kit and adjust the chemicals one week before you cover the pool. Target the following ranges:

• pH: 7.2 – 7.8 (ideal ~7.4).

• Total Alkalinity: 80 – 120 ppm.

• Calcium Hardness: 180 – 220 ppm (aim mid-range).

• Chlorine (free): about 1–3 ppm after shocking (see below).

• Salt (for saltwater pools): about 3,000–3,200 ppm (keep within manufacturer’s recommended range).

  
  

Aim for midpoints of each range. If needed, raise alkalinity and pH with baking soda or lower them with muriatic acid. Add calcium chloride to raise hardness. For saltwater pools, do not add extra salt before winter – adding salt can overshoot the level and cause scaling.

Saltwater Pool Tip: Leave salt levels on the lower end of the recommended range before closing, to avoid staining. The ideal salt level is about 3,200 ppm, so balance close to that without overshooting. If above 3,200 ppm, drain and top off with fresh water.

After balancing, shock the pool with a chlorine shock treatment (calcium hypochlorite or liquid bleach) to eliminate any lingering bacteria and organics. Run the pump 24 hours after shocking and retest chlorine – it should settle to ~1–3 ppm. Then add a dose of winter algaecide and a stain/preventer (winterizing chemicals) evenly around the pool. These keep the water sanitized and prevent algae over winter.

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3. Remove Accessories and Equipment

• Remove all accessories such as ladders, slides, floats and cleaners. Store them indoors or in a dry shed. Wash and dry these parts first (a baking soda paste works well) to avoid mold.

• Take off skimmer baskets and returns: Remove or cover the skimmer and return jets. You can use winter skimmer plates or plugs to seal off skimmer/return lines.

• Drain hoses and pipes: Disconnect hoses from the pump, filter, and chlorinator. Drain them completely (coil and bring them inside if possible). Any remaining water can freeze and crack hose fittings.

4. Lower the Water Level

Above-ground pools: Most above-ground pools are drained just a few inches below the skimmer opening or waterline. This ensures any snow or rain can overflow into the pool but stays below the skimmer when ice expands. Do not lower more than ~18 inches below the pool wall or skimmer to avoid damaging the liner.

• Mesh (safety) covers: If using a mesh cover, lower the water about 12–18 inches below the skimmer/waterline. This accounts for snow/rain entering the pool without lifting the cover.

• Solid (winter) covers: With a solid cover, lower roughly 6–12 inches below the skimmer or waterline (about half a foot) since no water will pass through.

  
  

Use your filter’s waste/drain valve or a submersible pump to remove water. You can also use the siphon method with a garden or vacuum hose. If you have a sand or D.E. filter, first backwash to clear out debris (careful not to let the pump run dry!). Follow manufacturer instructions: many recommend leaving water in the skimmer slightly to protect the basket.

5. Drain and Store Equipment

Properly draining your equipment is vital to prevent freeze damage:

• Pool pump and filter: Turn off power. Open and remove all drain plugs from the pump, filter, heater, chlorinator, and chlorinator cell. Tip the pump/filter on its side or upside-down to remove residual water. Clean or replace filter cartridges or grids (hose them off or soak in filter cleaner) before storing. Wipe and dry them thoroughly.

• Salt cell (saltwater pools only): For saltwater systems, remove the salt chlorinator cell by unscrewing its unions. Rinse it with a hose to remove scale (don’t use metal tools) and let it dry completely. Store the cell indoors for winter. You can insert a dummy cell to keep the plumbing sealed if desired.

• Skimmers and returns: Remove any skimmer baskets and drain plugs. Use a shop vac or blow compressor through skimmer and return lines to clear all water. Then insert expandable plugs in the skimmer and return line openings. This prevents freeze pressure in the plumbing. (Alternatively, pour nontoxic pool antifreeze into the lines per label instructions.)

• Other equipment: Blow out or tip any other plumbing lines (e.g. from solar heaters or additional sanitizers) and plug them. Store smaller parts (e.g. O-rings, drain plugs) in the pump basket or a labeled container so nothing is lost.

  
  

Any equipment that can be kept indoors (filter, pump, heater) should be. At minimum, ensure all equipment is bone-dry. Lubricate O-rings or valves lightly with silicone grease before storage to prevent cracking.

6. Place the Pool Air Pillow

For above-ground pools, an inflatable air pillow (also called ice compensator) is strongly recommended. This vinyl pillow goes between the water and the cover to absorb ice pressure. It prevents ice from pushing outward and damaging the pool walls.

How to install the pillow: Inflate it to about 60–80% capacity so it can compress under ice. Attach rope to the pillow’s grommets and secure the ends of the rope to the pool’s top rails or frame. Center the pillow in the pool, then carefully pull the cover over the pool (keeping the pillow under the cover). A helper or pole can assist in keeping the pillow centered as you settle the cover.

Tip: Use actual pool-grade air pillows; inner tubes or balls don’t work the same.

If you are looking for a high quality pool pillow at a reasonable price, check out the Poolhacker Pool Pillows.

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7. Install and Secure the Winter Cover

Choosing and securing your cover is the final step:

• Mesh vs. solid cover: Mesh (safety) covers let rain and snow through (collecting in the pool) and keep out large debris. Solid covers block everything, so rain/snow sit on top of the cover. Either type must be taut and tear-free. Patch any holes or frayed spots before installation.

• Positioning: Spread the cover over the pool so it fully overlaps the edges. For solid covers, attach water bags or weights around the perimeter on top of the cover to hold it down (12–24″ apart). For mesh/safety covers, anchor the cover straps to the deck anchors or through-warps around the pool. Above-ground pools often use a cable and winch kit under the top rails to cinch the cover tight. Check that the cover is pulled evenly; any sagging can collect water or debris.

• Securing against wind: Use cover clips, spring-covered straps, or extra anchors to prevent lift. With cable systems, tighten the winch fully so the cover can’t slip. If your cover came with a safety cover pump or absorbent sponge, place it according to instructions (often on top to soak any runoff).

  
  

Note: If using a solid cover, do not let large pools of water accumulate on top. Attach a cover pump (or siphon method) to remove water, or periodically roll up and drain any standing water to avoid excessive weight on the cover.

For round above ground pools, Poolhacker also do durable and reliable solid winter covers. It's heavy-weight construction and windproof features ensure your pool stays sealed and safe until the warm weather returns. These come 4' oversized. So if you buy a cover for a 22' pool, the cover will be 24' in diameter, which will allow for a 2' overhang all round the pool. Check out the Poolhacker Winter Covers.

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8. Pool Closing Final Safety Checks and Spring Prep

Once covered, do a final walkthrough:

• Clear the area: Remove any loose items or tools around the pool. Ensure the cover is secure using a cable system or winch kit (adding extra anchors if possible) to prevent accidents. Install a pool alarm or safety sign if needed.

• Check plugs and valves: Double-check that all drain plugs (pump, filter, heater) are out and stored safely, and that all plumbing or pool plugs are secure in the inlets/outlets.

• Schedule periodic checks: Throughout winter, remove snow and debris from the cover to prevent strain. Periodically check water chemistry (or at least salinity in a salt pool) every 6–8 weeks if practical, adding sanitizer/algaecide as needed. Use a cover pump or siphon method on solid covers to wick away water from snowmelt or heavy rains.

  
  

Finally, note down any details for spring: where you stored connectors, hoses, the locations of any o-rings and any supplies (new filter cartridges, winter chemicals) you’ll need. Keeping a checklist will make opening the pool a breeze.

With these steps complete, your pool is tucked safely away for winter. Enjoy peace of mind, and look forward to easy opening and clean water when the warm weather returns!