When is the best time to close or winterize my pool?

The golden rule of pool closing is the 65-degree rule. You should wait to close your pool until the water temperature consistently drops below 65°F (18°C). Algae struggles to grow in water colder than this. Closing too early while the water is still warm will deplete your winter chemicals and guarantee a green swamp when you open in the spring.

Do I need to blow out my pool lines for winter?

If you live in an area where the ground freezes during the winter (the Frost Belt), blowing out your underground plumbing lines with an air compressor and sealing them with winter plugs is absolutely mandatory. Freezing water expands and will shatter underground PVC pipes, resulting in a $5,000+ repair.

What is the difference between a mesh and solid winter cover?

A solid safety cover blocks all sunlight and water, keeping the pool perfectly clean, but requires a submersible cover pump on top to drain melting snow. A mesh safety cover lets rain and melting snow pass through into the pool. Because mesh lets in sunlight and water, you must open mesh-covered pools earlier in the spring before the water warms up to prevent algae.

Pool Opening & Closing Checklist Generator | Pool Checker

Free Tool

Pool Opening &
Closing Checklist

Stop dreading the start and end of the season. Generate a customized step-by-step checklist based on your specific climate and pool type.

How to Use This Generator

No two pools are the same. Winterizing a pool in Minnesota requires entirely different steps than shutting down a pool in Texas. Here is how to use this tool:

Select Your State: This is critical. The calculator will automatically determine if you are in a "Frost Belt" state that requires anti-freeze and air-purged plumbing lines.
Select Your Cover Type: Mesh covers and Solid covers require different water levels and chemical approaches.
Print Your Plan: Click the "Print Checklist" button on your generated plan, grab your tools, and follow the steps in exact order to protect your equipment.

The Science of the "65-Degree Rule"

The single biggest mistake pool owners make is closing their pool too early in the fall or opening it too late in the spring. You must follow the 65-Degree Rule.

Algae and bacteria require heat to rapidly multiply. When your pool water drops below 65°F (18°C), algae goes dormant. If you close your pool while the water is 75°F, the winterizing chemicals you add will be burned through in a matter of weeks, leaving your pool unprotected for months. The result? A dark green swamp when you take the cover off in May.

When to Close (Winterize)

Wait until the daytime high temperatures consistently keep your pool water below 65°F. Keep the pump running and maintain normal chlorine levels until closing day.

When to Open (Spring)

Open the pool before the water warms up. If you have a Mesh Cover (which lets sunlight in), you must open the pool the second the ice thaws to prevent a massive spring algae bloom.

Mesh vs. Solid Covers: What You Need to Know

If you generate a checklist above, you'll notice the instructions change drastically based on your cover. A Solid Safety Cover blocks 100% of sunlight and rainwater. This keeps your pool incredibly clean, but you must purchase a submersible cover pump to leave on top of the cover all winter so melting snow doesn't cave it in.

A Mesh Safety Cover allows rain and snow to drain into the pool. While you don't need a cover pump, the influx of rainwater will raise your pool's water level over the winter. If you live in an area with heavy precipitation, you may need to drop a pump into the pool mid-winter to drain excess water so it doesn't freeze and crack your decorative waterline tile.

Frequently Asked Questions

Do I really need to blow out my underground lines?

If you live in an area where the ground freezes (the Frost Belt), blowing out your plumbing lines with an air compressor and sealing them with expanding rubber winter plugs is absolutely mandatory. Freezing water expands with immense force and will shatter underground PVC pipes.

Can I just use my shop vac to blow the lines?

A powerful, high-HP wet/dry shop vac can work for short plumbing runs on small pools. However, for deeper pools or pools with main drains, a shop vac does not produce enough sustained air volume (CFM) to push the heavy water out of the deep end. Pool professionals use specialized, high-volume blowers (like the "Cyclone") to ensure lines are totally clear.

Should I add antifreeze to my pool lines?

Yes, in freezing climates. After blowing the lines, pouring non-toxic RV/Marine Pool Antifreeze into the pipes before plugging them provides an extra layer of insurance in case a plug fails or condensation accumulates. Never use automotive antifreeze.

Next Steps: Prepare for the Season

Once your pool is open, or right before you close it, you need to calculate your chemical needs to ensure the water stays pristine.

Calculate Seasonal Supplies Pool Volume Calculator