Here in the Northeast pool closing is a sad but critical task that means the swim season has concluded for the year. It’s important for pool owners to know that your pool must be closed properly to avoid unnecessary problems and costly repairs when the next swim season is upon you.

As the days are now getting shorter, and the kids are back in school the time is right to close your swimming pool. The best time to close is when night-time temperatures start to dip into the 40s and daytime temperatures are in the 60s to low 70s. Close much sooner and you risk an algae bloom, much later and you could be fishing out a lot of leaves.

In case you’ve ever wondered how the pool professionals do it (or are thinking of doing it yourself), here are the basics:

First make sure your water is properly balanced, with appropriate levels of pH, alkalinity and calcium hardness. Next check to make sure the water is neither corrosive (undersaturated) or scaling (oversaturated).

Then lower the water to the appropriate level for winter. Vinyl liner pools can stay as they are, but the water in a concrete or gunite pool should be six to eight inches below the tile line.

Next, clean the filter. DE (diatomaceous earth) or cartridge filters must be disassembled so that internal parts can be removed and cleaned, while sand filters must be thoroughly backwashed.

Then blow out the return and skimmer lines to remove all the water from them, then plug them with either rubber or threaded plugs, depending on the type of pool (our retail shop can advise you). Lines that are not blown out can freeze and burst, crippling your pool and calling for expensive repairs to install new lines under concrete. If you’re closing your pool yourself, you will have to rent a blower or an air compressor to complete this step.

The next step is to remove the drain plugs from the filter, filter pump, heater, chlorinator and any other equipment that needs to be drained, such as a waterfall pump. Failure to drain the pool heater correctly can lead to water freezing in the heat exchanger and another expensive repair. Make sure to turn off the power on all equipment, so it doesn’t kick on later by itself. The gas needs to be turned off on the gas heater, on and off switches removed from timers, and any auto controls deactivated.

Finally, add winterization chemicals, including an algicide and stain and scale preventative. The chemicals needed vary according to the size of your pool and type of pool cover. Once these are added, we remove the ladders and install your pool cover.

If you’re closing the pool yourself, you can finally have the beverage of your choice and relax! If you would rather skip the work, and just relax, give your pool professional a call.