How to Winterize an Inground Pool in 10 Steps

How to winterize an Inground Pool
by Rob Cox, September 27, 2010

How to Winterize an Inground Pool in 10 Steps

how to close your inground swimming pool
For those of us living in the snowbelt, it seems that another season has slipped by. Temperatures are approaching 32 degrees in some parts of the country, and unless your pool pump is running all night long, freeze damage can result. Pipes, heaters, filters, pumps - all are made from strong materials, but all will crack from the expansion of ice within unless proper precautions are taken.

This article will explain how to winterize your inground pool. All pools are slightly different in their configuration, so use these tips with caution. If you have questions on your specific pool and the closing process, get in touch with us, and we'll help make sure you are well protected from winter's worst.

1. Balance your pool water. Adjust your pH, total alkalinity and calcium hardness levels in the pool. It's best to do this about a week prior to your pool closing to make sure that further adjustment is not needed. Shocking the pool with granular chlorine is a good idea before closing the pool, but this should also be done a few days or a week prior to closing. This will allow the chlorine level to drop before putting your pool cover on the pool. High chlorine levels can weaken your winter pool cover and destroy your winter algaecide, so carefully monitor chemical levels leading up to the closing date when they are added.

2. Clean the pool thoroughly. The cleaner the pool is when you close it, the better it will look next spring. Any debris or algae left in the pool during closing will dilute the strength of your winterizing pool chemicals. These chemicals work on organic matter left in the pool, so a dirty pool leaves less available algae prevention during the winter.

3. Lower the pool water. For mesh safety covers, the water level should be 8-12" below the tile. For solid pool covers, the type that float on the surface and are held in place with water bags, lower the pool water level 3-5" below the tile. If you have an inground vinyl liner, you can also make use of a product called a skimmer plug, which is almost like Tupperware lid for your skimmer. Just snap it on the front of the skimmer, and you don't need to lower the water level at all.

4. Add winter pool chemicals. Many pool owners use a pool closing kit, which usually contains algaecide, borate floaters, stain and scale preventer and some non-chlorine shock. Follow the instructions on the package. These instructions usually recommend adding the chemicals before lowering the pool water. However, some prefer to add them after lowering the water level so that the chemical concentration is stronger. Broadcast the chemicals broadly over the pool surface, and use a pool brush to help distribute. If you have a mesh safety cover, we recommend using a pool enzyme product to help control algae growth during the winter. It's also helpful to check the water chemistry during mid-spring (about a month before opening), and add another quart of algaecide or refill the floating chemical dispenser.

5. Clean the pool filter. For DE filters, remove the assembly from the filter tank and hose it clean to remove all DE powder. DE powder left to dry on the grids during the winter can cause clogging of the fabric, creating filtration problems the following spring. If you have a cartridge filter, the same rule applies: remove the cartridge and hose thoroughly. After blowing the lines, place your grid assembly or filter cartridge back in the filter tank for safekeeping during the winter. Make sure that you tightly secure the filter lid and clamp band before and after blowing lines. Loose or improperly secured filter clamp bands can cause the filter lid to blow off during start-up, with disastrous or fatal results.

6. Remove drain plugs. They'll need to be removed from the pool pump(s), filter, heater and chlorinators. Look over all the pipes and every piece of equipment, looking for and removing any drain plugs you see. Open all directional valves to allow the water level to fall to the level of the water in the pool.

7. Blow the lines out with air. This is the most important step in the process. Blowing out the equipment and plumbing ensures that there is no water left that can cause freeze damage. If you choose not to blow out the lines, make sure that all of the equipment is completely drained, and add non-toxic pool antifreeze the plumbing lines.

You can blow out the lines using a Cyclone blower, or you can use a powerful shop vac or small air compressor. Direct the air backwards through the suction lines to blow out the skimmer. Once the suction lines are plugged, direct the air through the pump (removing the volute drain plug) through the filter, heater, chlorinator, and finally out of the pool return lines.

8. Plug the lines. Use pool plugs to plug skimmers, returns and cleaner lines. Make sure to plug them all! You don't want any pool water returning to the lines after you've winterized them.

9. Add skimmer bottles. You can use a skimmer guard, which is a combination skimmer plug and ice absorption device. If you are plugging the skimmers with rubber freeze plugs, then use a 1 qt. or 1 gallon bottle, empty except for a few inches of either antifreeze or small pebbles in the bottom. This will weigh the bottle down and allow it to float partially submerged. When the water rises in the skimmer and freezes, the expansion of the ice will collapse the bottle or skimmer guard and not break the outside walls of your skimmer.

10. Shut off power to the pump. Do this by turning off the circuit breaker. It's also a good idea to remove any timer dogs on the timeclock, just in case someone turns the breaker back on during the winter.

That's about it! As mentioned earlier, every pool is a llittle different. Just make sure that all of the water is removed from the plumbing (with the exception of the main drain, which may not blow out) and from the equipment. Do NOT cover the equipment with plastic, as this can trap moisture and create rust. That said, heater covers are still a good idea. If you have any questions on winterizing your swimming pool, just click the link at the top of the page and let us know. You can do this!