10 Steps to Winterize an In-Ground Pool

WINTER IS HERE! Prepare your beloved swimming pool for the cold season with these easy-to-follow steps!

Step 1: Balance the pool water

To accomplish completely balanced water, you’ll need to adjust the pH, calcium hardness, and total alkalinity levels of your pool. You should do this a week or several days before you close your pool to ensure that you won’t be making adjustments in the future anymore. It’s also a great idea to shock your pool using granular chlorine before you close the pool. However, this must also be performed a week before closing to enable the chlorine level to decrease before you place the pool cover on your pool. High chlorine levels can weaken the pool cover, and that’s why you shouldn’t allow highly chlorinated pool water to make contact with the cover.

Step 2: Thoroughly clean the pool

Dolphin 99996403-PC Dolphin Nautilus PlusYou could use any type of cleaner you prefer for this step, just make sure no debris or algae remains after cleaning. It’s essential for the pool to be clean before winter to prevent the growth of algae and increase of bacteria in your pool.

Don’t forget to run the pool as well to enable the filter to clean out small particles that may be invisible to the naked eye. Make sure that the remaining water is as clean as a whistle. Chemical cleaners can also help so you should consider using them too. If you have an automatic in-ground cleaner, then switch it on and let it do its job.

Step 3: Drain out the water partially

Next, you partly get rid of the water. If you own a solid pool cover, the one that floats on the surface and is held in position with water bags, you’ll need to lower the level of pool water 3-5 inches below the tile. On the other hand, if you own a mesh safety cover, the pool water level should be 8-12 inches below the tile. You could use Aquador if you have an in-ground vinyl liner. This product can be snapped on the front of your skimmer so that you no longer have to decrease the water level.

Step 4: Clean the filter

Next, you need to remove the pool filter so that you can thoroughly clean it. The cleaning process depends on the type of filter you have. If you have a sand filter, just remove and backwash it. If you own a cartridge filter, just remove it as well and backwash it using your garden hose. The same goes if you have a DE filter: remove then backwash all the DE powder. Remember that the DE powder that’s left to dry on the grids during the cold season may cause clogging of the fabric, leading to filtration problems on the next season. After cleaning the filter, return it to the tank for storage during winter. Ensure that the filter lid and clamp band are secured before and after blowing lines. If they’re loose, they can cause the lid of the filter to blow off while starting up.

Step 5: Add the pool chemicals

Don’t just add any chemical, add the winter pool chemicals. You could use a pool closing kit that contains algaecide, stain & scale, borate floaters, and non-chlorine shock. You only have to follow the instructions stated on the package. However, these packages usually recommend adding the chemicals before lowering the pool water level, but I suggest you do otherwise (add the substances after) so that the concentration is stronger. Just scatter the chemicals over the surface of your pool and use a pool brush to distribute it evenly. Use a pool enzyme product to help control the growth of algae if you have a mesh safety cover. During mid-spring or a month before you open the pool, it would help if you check the water chemistry and refill the floating chemical dispenser or add another quart of algaecide.

Step 6: Get rid of the drain plugs

Remove the plugs from your pump/s, heater, filter, and chlorinators. Check all pipes and pieces of equipment, then remove any drain plugs. Also, open the directional valves to enable the pool water level to drop.

Step 7: Blow the lines with air

Warning: Do not skip this step. This is probably the most significant step in this winterizing procedure.

Blow out the equipment and plumbing to make sure no remaining water can cause freeze damage. If you don’t prefer doing this, then there is an alternative: ensure that all of the equipment is entirely drained and that you add a non-toxic pool antifreeze to the plumbing lines.

Step 8: Plug the lines

Use expansion plugs or freeze plugs for your skimmers, cleaner lines, and returns. Don’t leave any line unplugged.

Step 9: Add the skimmer bottles

Gizzmo is both a skimmer plug and an ice absorption device which is useful at this stage. If you’re plugging your skimmers using rubber freeze plugs, merely use a quart or a gallon bottle, empty except for one or two inches of either small pebbles or antifreeze. This will help weigh the bottle down and enable it to float while being partially immersed. When the water ascends in the skimmer then freezes, the expansion of the ice will collapse the bottle instead of the outside walls of the skimmer. It’s quite impressive if you ask me.

Step 10: Cover the pool


Cover your pool! This last step requires you to shut the power to the pump by switching the circuit breaker off. This is also the best time to get rid of any timer dogs on the time clock because you’ll never know if there’s someone who might switch the breaker back on during the cold season.

Parting Words

Since each pool is a bit different from another, you have to ensure that you’ve dealt with all the winterizing requirements of your pool and that all the water is gone from the equipment and plumbing (except the main drain which might not blow out). Whatever you do, don’t ever use a plastic cover for your equipment. Plastics can confine moisture and produce rust. However, heater covers are recommended.

Ready or not, you’ll have to do this winterizing soon. If you have queries, don’t hesitate to contact us. And don’t you worry; you can do it!