1. Balance The Water
About 4-7 days prior to closing your pool for winter, bring your pool pH (7.6-7.8), pool alkalinity (80-100), and calcium hardness (150-250) in line. Shock the pool with a chlorine shock to bring the chlorine level up to 10-12ppm. Allow the pool chlorine to come down to its normal level, about 1.5-3.5ppm before adding any pool algaecides, pool winterizing chemicals, or your pool cover. If you are unsure of how to correctly balance the water, take a sample to your local pool retailer and they can test it and make recommendations.
2. Removal Of Inground and Above Ground Pool Accessories
Remove the skimmer baskets, heaters, slide, any wall fittings, vacuums, pool cleaners, ladders, handrails, or anything else that shouldn't be in the pool. Scoop out any debris on the top and bottom of the pool using a good leaf rake. At this point you may want to invest in a winter conditioner or a winterization swimming pool water treatment kit to keep your pool water chemistry on track. You can visit a local pool professional retailer to get all you need for your inground and above ground pool chemicals.
3. Clean And Backwash The Filter
You'll want to do one final brush and vacuum to winterize your swimming pool. Once this is done, it's time to backwash your filter.
4. Lower The Water Level
You can either use your filter pump or a submersible pump to lower your pool water level. You'll need to lower the level about 4"-6" below the lowest plumbing line, normally the water return line. Be sure the water level is at least below the skimmer. You can remove the above ground pool skimmer.
5. Drain Your Pump, Filters, Heaters, and Chlorinating Equipment
Your pump, filter, heater, and chlorinator all have a drain plug. Either drain the water out of these or blow the line out with a shop vac. This will ensure all of the water has drained and none is left inside any plumbing lines. If you have a DE pool Filter or a cartridge filter, now would be a good time to take them out and clean the grids or cartridges and store them away for the winter. If the filter is small enough, you might be able to take it apart and store it for the winter. Keep the plugs out of these units. If you plug them back up and water happens to get into them, they might freeze over and crack your equipment. Place all the plugs in the skimmer basket during your pool winterization maintenance. By doing this, you'll know where they are when you need them next spring.
6. Empty Your Chemical Feeder
If you have a chemical feeder, now would be a good time to drain and empty it. By leaving chemicals in your chemical feeder during swimming pool winterization, you might damage your equipment. Remember to put the top back on the chemical feeder and be sure to wear safety goggles and gloves.
7. Winter Pool Covers
Now is the time to break out your above ground pool winter cover or inground pool winter cover to keep the debris out of the pool. Use a solid cover that keeps out all debris and sun. These solid covers should keep the pool clean and prevent algae growth. You should also use an air pillow. These air pillows hold the pool cover up like a tent so water and debris fall off instead of collecting on the top. They also help to take up any water expansion which could occur from freezing and possibly cause your above ground pool wall to split.