Whether you have an above-ground or in-ground pool, there are three basic steps for winterizing:

1. Balance the water chemistry.

About a week before you close your swimming pool, adjust the water chemistry to the following levels:

  • pH: 7.2–7.6
  • alkalinity: 80-120 ppm (parts per million)
  • calcium hardness: 180-220 ppm

Then, shock the pool with chlorine with chlorine or a non-chlorine substitute to kill any lingering germs. Let the chlorine level return to 1-3 ppm over the next few days before proceeding.

Next, add a winterizing algaecide. Don’t add it until chlorine levels are back to normal; you want the algaecide to stick around, and chlorine in high concentrations will break it down.

2. Clean everything out.

This includes ladders, baskets, wall fittings, hoses, pumps, filters, heaters and anything else in your swimming pool that’s not water. Let everything dry completely before storing in a protected area. Pull the drain plugs on all filters and pumps to ensure all the water gets out.

After everything’s removed, it’s time to skim, vacuum, and brush your pool. Be thorough; the cleaner your pool is now, the less work you’ll have to do in the spring.

3. Cover your pool.

Before putting the cover on, you’ll need to lower the water level. How low you go depends on your cover. If it’s mesh, which is common in warmer climates, decrease the water level 12 to 18 inches below the bottom of the cover. Solid, floating covers should go 3 to 6 inches below the top edge of the pool. If you have an above-ground pool, lower the water level 4 to 6 inches. This YouTube video has more information on how to lower your water level before winter starts.

Make sure the cover fits tightly — there should be no gaps where leaves or critters might fall in.

Courtney Craig is an Atlanta-based writer and editor. She believes no effort is too small when it comes to green living, which she blogs about at The Greenists, a site she co-founded.