Do I Need Pool Antifreeze? Complete Winterizing Guide

Do people actually use antifreeze in their pool? Yes, some do, but it is typically an optional extra, not a required part of closing. The essential process for protecting plumbing from freezing involves blowing out the lines with compressed air, then plugging openings. Non-toxic antifreeze, if used at all, serves as a secondary safeguard for lines that might retain some water and is poured directly into the plumbing—never into the pool water itself. You must never use automotive antifreeze.

When You Might Use Pool Antifreeze

For pool owners in freezing climates, the main objective of winterization is to stop water inside pipes from freezing and causing cracks. Blowing out the lines with air is the fundamental method. Adding antifreeze is an additional measure some take for extra peace of mind.

Understanding Pool Antifreeze Types

Automotive antifreeze is never safe for pool systems. It contains toxic ethylene glycol, which can harm equipment and pollute the water.

If you decide to use antifreeze, select a product labeled for pool or RV plumbing, which will be propylene glycol or a blend containing it.

Where to Use Pool Antifreeze

Antifreeze should be poured into the plumbing line before installing a winter plug or Gizzmo, allowing it to travel into the pipe.

Skimmer Lines

After blowing out the skimmer line, you can pour antifreeze into the skimmer port before plugging it if you suspect water remains. The skimmer well itself is not filled; you plug the port and usually place a compressible object, like a half-filled plastic bottle, in the well to manage ice expansion.

Return Lines

If a return line might not be fully clear, antifreeze can be added through the return fitting prior to plugging it.

Main Drain Lines

Protection for the main drain line comes from blowing it out and then closing its valve at the equipment pad while air is still flowing, which creates an air lock. Filling it with antifreeze is uncommon.

How Much Antifreeze to Use

There is no universal amount, as it depends on your specific plumbing layout and how well a line was cleared. Follow the directions on the product label. It is intended only for individual lines you are concerned about.

Proper Application Method

1. Blow out lines first: Use an air compressor or shop vacuum to force as much water as possible from all plumbing.
2. Add antifreeze before plugging: Install skimmer and return plugs only after pouring in antifreeze, so it flows into the pipes.
3. Pour slowly: Add antifreeze directly into skimmer ports and return fittings, letting it travel down the lines.
4. Check for leaks: Make sure antifreeze isn't seeping out from around plugs or fittings.

Regional Considerations

Northern Climates

In areas with harsh winters, a complete air blow-out and secure plugging are critical. Antifreeze can act as a backup for plumbing that is hard to clear entirely.

Moderate Climates

Where freezes are infrequent, a proper blow-out and plugging is often enough protection.

Mild Climates

Regions with mild winters typically do not need to winterize plumbing lines.

Alternatives to Antifreeze

Some owners employ different strategies to prevent freeze damage:

• Freeze protection devices: Automated systems that turn the pump on when temperatures fall.
• Partial winterization: Running the pool equipment occasionally during the cold season.
• Pool covers with air pillows: These help absorb pressure from expanding ice against the pool walls.

These approaches can be effective but require attention and may increase energy costs.

Spring Opening Considerations

You do not need to remove antifreeze when opening your pool. Propylene glycol will dilute without harm as you refill the pool. If a large quantity was used, the water may feel slightly slippery at first, but this will dissipate after a few days of normal circulation and filtering.

Proceed with your standard water testing and balancing routine. At the diluted levels present after refilling, antifreeze does not meaningfully affect pH, alkalinity, or sanitizer levels.

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