Step-by-Step Guide to Winterizing Your Gibraltar Pool

The Ultimate Checklist for Winterizing Your Gibraltar Pools™

The dog days of summer are coming to a close. For pool owners, this seasonal shift means one important task is on the horizon: it's time to winterize your pool.

Closing your pool for the off-season is one of the most critical maintenance tasks you'll perform all year. It not only helps protect your investment from freezing temperatures and potential damage but also makes reopening your pool in the spring much easier and stress-free.

Whether this is your first time winterizing a swimming pool or you've done it once or twice before, the entire process can seem intimidating every time the season rolls around. Fortunately, our professionals are here to guide you through every step of pool winterization. Let's get started!

Before you begin, it's best to gather all your tools and supplies in one place. This will streamline the process and prevent you from having to stop midway through to search for a missing plug or chemical.

Your Winterizing Supply Kit:

  • Winterizing Chemical Kit: These kits typically contain everything you need, including a winter-grade algaecide, stain and scale preventer, and pool shock.
  • Water Testing Kit: To balance your water one last time.
  • Pool Cleaning Equipment: Skimmer net, leaf rake, wall brush, and pool vacuum.
  • Winter Cover & Accessories: Your heavy-duty cover, cover clips, and an air pillow.

Plumbing & Equipment Supplies:

  • Winterizing plugs for the return jet(s).
  • A skimmer winterizing plate or a Gizzmo-style threaded plug.
  • A shop vacuum or air compressor (for blowing out the lines).
  • Non-toxic pool antifreeze (recommended for climates with deep freezes).
  • Basic tools like wrenches for removing drain plugs.

Step 1: Clean the Pool Thoroughly

About 5–7 days before your planned closing day, give your pool a thorough cleaning. Use your skimmer net to remove any leaves, insects, or debris floating on the surface. Then, brush the sides and floor to loosen any algae or buildup, and vacuum the pool completely.

Note: The cleaner your pool is when you close it, the less chance you'll have of dealing with staining, scaling, or algae growth when you reopen it.

Step 2: Balance the Water Chemistry

Next, use your water testing kit to check the key chemical levels. Adjust them to fall within these ideal winter ranges:

  • pH: 7.2–7.6
  • Total Alkalinity: 80–120 ppm (parts per million)
  • Calcium Hardness: 180–220 ppm
  • Chlorine: 1–3 ppm

Allow the pump to run for several hours after adding any balancing chemicals to ensure they are fully circulated. Balanced water prevents corrosion, scaling, and liner damage during the off-season, which ultimately helps your pool last longer.

Step 3: Add Winterizing Chemicals

With the pool sparkling clean and the water balanced, it's time to add your winterizing chemicals. This step is crucial for keeping the water clear until spring.

  • Shock the Pool: Add a granular pool shock according to the manufacturer's instructions. A non-chlorine shock is an excellent choice for closing, as it won't bleach or damage your liner over the winter months. Pre-dissolve the shock in a bucket of pool water before broadcasting it evenly across the pool's surface.
  • Add Algaecide: After letting the shock circulate for a few hours, add your winter algaecide. The algaecide will prevent algae spores from blooming and settling on and staining your pool's surfaces.

Step 4: Lower the Water Level

To protect your skimmer and return lines from ice damage, you need to lower the water level. For a Gibraltar Pools™, the ideal level is approximately 4–6 inches below the bottom of the skimmer opening. This ensures that no water can enter the skimmer once it's plugged. You can lower the water using your filter pump's