HOW TO CLOSE AN ABOVE GROUND POOL?
In order to open the pool in the spring with less hassle, it is preferable to close the pool as late as possible in the fall (water temperature at 50°F or less), keeping the water clean, clear and balanced, of course. The vinyl liner will be exposed to the sun for a shorter period, thus less subject to drying and fading.
Have a complete water analysis done a few days before you plan to close the pool in order to have time as the total alkalinity should be at 150 ppm and the pH between 7.6 and 7.8
As for the filtration system and all connections, if you take the time to label them, make a drawing or take a picture of the installation, you will avoid a headache next spring.
Repairs, if needed, should be done before you close the pool.
Bring the water level about 12 to 18 inches below the skimmer by using "DRAIN" or "WASTE" on the filter.
While the water is coming down, you can remove the ladder / steps (if they are still there). Disconnect any and all timers!!!
Winterize the heater if you have one.
Turn off the electricity. If gas, turn off the pilot and the gas intake. Disconnect the hoses and make sure there is no water left inside, using a vacuum.
If you have lights: Turn off the electricity or unplug.
If it's an Aqua-Luminator, once the water level is below it, remove the bulb.
Remove chemicals from the chlorinator / brominator and remove drain plugs.
Once the water is low enough, turn off the pump, set the filter to "WINTERIZE" or "CLOSE". Remove the pressure gauge, bottle (if there is one) and drain plug from the filter.
If you bring the pump inside, disconnect hoses from it and apply some lubricating silicone to the cover o'ring and remove the drain plug.
If you have a bottom drain, you can leave it connected to the 3-way valve under the skimmer, or disconnect it and connect a hose or some pvc to have the top above the pool (the water level will rise with the rain and snow). Next, remove the door and basket from the skimmer. Put some anti-freeze in that hose, along with a 4' section of grey foam. If still connected to the 3 way valve, place the handle to close off that connection. Insert the foam in the skimmer.
If you have a cartridge filter, remove the cartridge, clean it and let dry.
Before you install a net or winter cover, put in the closing kit.
If you install a net or winter cover, install an inflated air pillow 4' x 5' beforehand to help keep the net or cover above the water.