How to Winterize Your Pool: A Complete Checklist

As swimming season comes to an end, properly closing or "winterizing" your pool is one of the most important maintenance routines you'll perform all year. A correct closing protects your pool and its equipment from freeze damage, saves you from a green, swampy mess in the spring, and ultimately saves you time and money. This guide provides a comprehensive checklist to help you close your pool like a pro.

When should you close your pool? Wait until the water temperature is consistently below 65°F (18°C). Algae struggles to grow in cooler water, so closing it too early when it's still warm can lead to a green pool when you open the cover.

Step 1: Deep Clean the Pool (One Week Before Closing)

You want your pool to be as clean as possible before it goes into hibernation. About a week before you plan to close, give it a thorough cleaning.

• Remove all items: Take ladders, handrails, toys, and automatic cleaners out of the pool.
• Skim, Brush, and Vacuum: Skim all floating debris. Brush the walls and floor thoroughly. Give the pool a final, detailed vacuuming to remove all sediment. The fewer contaminants you leave in the water, the less work your winter chemicals have to do.

Step 2: Balance Water Chemistry (2-5 Days Before Closing)

Balanced water is stable water. It's crucial for protecting your pool surfaces from staining and scaling over the winter. Test and adjust your chemicals in this order, allowing several hours of circulation between additions.

1. Total Alkalinity (TA): Adjust to 80-120 ppm. Use our TA Calculator.
2. pH: Adjust to 7.4-7.6. Use our pH Calculator.
3. Calcium Hardness (CH): Adjust to 200-400 ppm. Use our CH Calculator.
4. For Saltwater Pools: Check your salt level with our Pool Salt Calculator. Your salt cell will not operate in cold water, but you want the level to be correct for a quick startup in the spring. Do not add salt right before closing; do it a week or two earlier to ensure it fully dissolves.

Step 3: Add Winterizing Chemicals (The Day of Closing)

With the water balanced, it's time to add chemicals that will keep the water protected through the winter months.

• Winter Algaecide: Add a dose of a specially formulated winter algaecide. This is a long-lasting product designed to prevent algae growth in cold water. Follow the product's dosage instructions.
• Stain & Scale Preventer: Adding a sequestering agent helps prevent minerals and metals from precipitating out of the water and staining your pool surfaces.
• Shock the Pool: The final chemical step is to shock the pool. This raises the chlorine level significantly to kill off any remaining bacteria or algae. Use a granular shock and follow the dosage on the package, or use our Pool Shock Calculator for a precise amount.

Note: Do not add all chemicals at once. Add one, let it circulate for an hour or so, then add the next.

Step 4: Prepare the Plumbing and Equipment

This is the most critical step for preventing freeze damage, which can lead to costly repairs. The goal is to remove all water from the pipes and equipment.

1. Lower the Water Level: Lower the water level in your pool to about 4-6 inches below the skimmer opening. This is crucial to prevent water from getting into the skimmer and freezing. You can use your pump's 'waste' setting or a submersible pump.
2. Blow Out the Lines: Use an air compressor or a powerful shop vac (on the 'blow' setting) to blow all the water out of the plumbing lines. Force air through the skimmer lines, main drain lines (if applicable), and return lines until you see bubbles coming out the other end and then just air. This must be done thoroughly.
3. Plug the Lines: Once a line is clear of water, plug it securely with a winterization plug (expansion plug) at the pool end (in the return jets and skimmer).
4. Drain Equipment: Remove all drain plugs from your pump, filter, heater, and chlorinator. This will allow any remaining water to drain out completely. It's a good idea to store the plugs in the pump basket so you don't lose them.
5. Disconnect and Store: If possible, disconnect your pump and filter and store them in a protected area like a shed or garage. If you can't, ensure they are completely drained and loosely covered. For saltwater pools, remove the salt cell, clean it, and store it indoors.

Step 5: Cover the Pool

The final step is to cover your pool securely for the winter.

• Choose the Right Cover: A proper winter safety cover is the best option. These are tightly woven covers that are anchored to the pool deck. They prevent debris from entering the pool and are strong enough to prevent people or animals from accidentally falling in. Avoid using a simple summer solar cover, as it will not withstand winter weather.
• Secure the Cover: Ensure the cover is pulled taut and securely anchored according to the manufacturer's instructions. Check it periodically throughout the winter to ensure it remains secure and to remove any large debris or excess water.

By taking the time to winterize your pool correctly, you are protecting your investment and setting yourself up for a much easier and faster pool opening in the spring. It's a weekend of work that pays dividends for months to come.