Skipping the winterization process is the fastest way to destroy a pool liner, crack a filter housing, or split a pump volute over a single hard freeze. Knowing how to winterize an above ground pool properly takes about 3 to 4 hours and protects thousands of dollars in equipment. Start the process when daytime temperatures consistently stay below 65 degrees Fahrenheit, typically late September through mid-November depending on your climate zone.
Balance the Water Chemistry First
Adjust chemical levels before adding any winterizing products. Target these ranges:
- pH: 7.2 to 7.6
- Total alkalinity: 80 to 120 ppm
- Calcium hardness: 175 to 250 ppm
- Free chlorine: 1 to 3 ppm
Balanced water prevents staining, scale buildup, and algae growth under the cover. Test with a reliable liquid test kit or take a sample to your local pool store. Strip tests work but are less accurate for calcium hardness readings.
Deep Clean the Pool
Brush the walls and floor thoroughly, focusing on the waterline where oils and minerals concentrate. Vacuum the bottom to waste if your filter valve has that setting, or vacuum to the filter and backwash afterward. Clean the skimmer basket and pump strainer basket.
Remove ladders, return fittings, and any accessories. Wipe them down, let them dry completely, and store them indoors or in a shed. Moisture left on metal parts causes corrosion over winter, and UV-damaged plastic components become brittle in freezing temperatures.
Add Winterizing Chemicals
A winterizing chemical kit for a pool up to 15,000 gallons costs $25 to $50 and typically includes a concentrated algaecide, an oxidizer shock treatment, and a stain-prevention sequestrant. Add the shock first with the pump running, wait 15 minutes, then add the algaecide and sequestrant.
Run the pump for at least 2 hours after adding chemicals to distribute them evenly. Some pool owners also add an enzyme product that breaks down organic contaminants through the winter, reducing the green soup that often greets you at spring opening. These enzyme treatments run $15 to $30 and are worth the investment.
Lower the Water Level
Drop the water 4 to 6 inches below the skimmer opening. Use the pump’s drain setting or attach a submersible pump. Do not drain the pool completely. The water weight holds the liner in place and prevents it from shrinking in cold temperatures. A liner that pulls away from the track is extremely difficult to reset and often tears during the process.
In regions where temperatures regularly drop below 0 degrees Fahrenheit, some owners lower the water 12 to 18 inches to account for ice expansion. Check your pool manufacturer’s guidelines for your specific model before going lower than 6 inches.
Blow Out and Plug the Plumbing Lines
Disconnect hoses from the skimmer and return jet. Use a shop vacuum set to blow or a small air compressor to force water out of each line. Insert threaded winter plugs into the return fitting and skimmer opening. Gizzmo-style skimmer plugs absorb ice expansion pressure and protect the skimmer housing from cracking.
Remove the drain plug from the pump, filter, and heater if you have one. Store plugs in the pump basket so you can find them in spring. Tilt the pump and filter to drain any remaining water. Even a small amount of trapped water can freeze, expand, and crack housings that cost $150 to $400 to replace.
Install the Winter Cover
Standard winter covers for above ground pools use a cable and winch system that tightens around the top rail. Size the cover to overlap the wall by at least 12 inches on all sides. A quality solid cover runs $50 to $150 for round pools up to 24 feet.
Thread the cable through the grommets, drape the cover over the pool, and tighten the winch until the cover sits snugly against the wall. Place an air pillow in the center of the pool before covering. The pillow absorbs ice expansion pressure and prevents the cover from collecting a heavy, centered water load that can pull it into the pool.
Secure the cover’s edge with winter cover clips that snap onto the top rail every 3 to 4 feet. Wind is the main enemy of pool covers, and a single strong gust can pull an unsecured cover off and into the yard.
Ongoing Winter Maintenance
Check the cover after every storm. Remove standing water with a cover pump ($25 to $50) before it accumulates more than 2 to 3 inches. Heavy water or snow loads stretch and damage the cover fabric and can collapse the pool wall in extreme cases.
Inspect the air pillow monthly. If it deflates, the cover sags into the water and collects debris that accelerates wear. Keep a backup pillow on hand since they occasionally puncture mid-season. Do not walk on the cover or allow pets on it. Solid covers are not safety covers and cannot support weight.
Following these steps on how to winterize an above ground pool each fall protects your investment and makes spring opening dramatically easier. A properly winterized pool opens in 1 to 2 hours instead of the days-long algae battle that comes from cutting corners.
