Figuring out how to winterize above ground pool with sand filter setups doesn't have to be a massive headache before the first frost hits. If you're like most pool owners, you probably want to procrastinate this chore as long as possible, but trust me, spending a few hours on it now is way better than dealing with a cracked filter tank or a swampy mess next May. It's all about protecting your investment and making sure the expanding ice doesn't wreak havoc on your plumbing.
Start with a deep clean
Before you even think about the filter or the cover, you've got to get that water crystal clear. It might seem pointless to clean a pool you're about to close, but any dirt, leaves, or dead bugs left behind will basically marinate all winter. That leads to nasty stains and a much harder opening day.
Give the walls a good scrub with a pool brush and vacuum the floor thoroughly. If you have a lot of debris, you might even want to vacuum "to waste" so you aren't sending all that gunk through your sand. Once the pool looks like you're ready to jump in, you're actually ready to start the closing process.
Balance your water chemistry
You don't want to just toss a cover on and hope for the best. Your water chemistry needs to be spot-on so the water doesn't become corrosive or scale-heavy over the next few months. Generally, you want your pH between 7.2 and 7.6 and your alkalinity between 80 and 120 ppm.
About a week before you officially close, it's a smart move to add a winterizing chemical kit. These usually include a concentrated algaecide and some long-lasting shock. Be careful with chlorine shock, though; if you use too much right before putting the cover on, it can actually bleach your liner or eat away at the cover itself. Let the pump circulate those chemicals for at least 24 hours before moving on to the mechanical stuff.
How to handle the sand filter
This is the most critical part for anyone wondering how to winterize above ground pool with sand filter systems specifically. Sand filters hold a lot of water, and since water expands when it freezes, an undrained filter is basically a ticking time bomb.
Backwash and rinse
Start by giving the filter a really long backwash. You want that sand as clean as possible before it sits dormant for months. Follow it up with a 30-second rinse to settle the sand back down. Once that's done, turn off the pump and pull the power plug.
Drain the tank
At the bottom of your sand filter tank, there's a small drain plug. Unscrew it and let the water pour out. This can take a while—sometimes an hour or more—because the water has to seep through all that sand to get out. Don't rush it. I usually just leave the plug off and put it in the pump basket so I don't lose it.
The Multiport Valve
Setting your multiport valve correctly is a "pro tip" that many people skip. You don't want to leave it on "Filter" or "Backwash." Most valves have a "Winterize" or "Winter" setting, which is basically a notch that lifts the internal diverter. This prevents the gasket inside (the spider gasket) from getting squished and stuck over the winter. If yours doesn't have a specific winter setting, just leave the handle somewhere between two regular positions.
Disconnect the pump and hoses
Leaving your pump outside in the snow and ice is just asking for a seized motor. Once the lines are drained, disconnect the hoses from the pool and the filter.
Take the pump motor inside a garage or basement. While you're at it, check the pump basket for any lingering debris and make sure the housing is empty of water. If you leave water in the pump, it'll crack just as easily as the filter tank. As for the hoses, if they're the cheap corrugated kind, they often get brittle in the cold. It's usually best to store them somewhere where they won't be stepped on or frozen.
Protecting the skimmer and return lines
Since this is an above-ground pool, you have a couple of options for the skimmer. You can lower the water level below the skimmer mouth, which is the traditional way, or you can use a "skimmer plate."
If you choose to keep the water level high (which helps support the pool walls against wind), you'll need a plastic cover that screws onto the front of the skimmer to keep water out of the throat. For the return line (where the water shoots back into the pool), unscrew the eyeball fitting and replace it with a solid threaded winter plug. This keeps the plumbing dry even if the water level rises from rain or melting snow.
The air pillow trick
If you live somewhere where the water is going to freeze solid, you must use an air pillow. This is just a heavy-duty inflatable pillow that sits in the middle of the pool under the cover.
A lot of people think the pillow is there to keep the cover up, but that's not it. It's actually an "ice compensator." When the water freezes into a giant ice sheet, it expands outward. Without a pillow, that ice pushes directly against your pool walls, which can literally rip the steel frame apart. The pillow creates a void in the ice; when the ice expands, it crushes the pillow instead of your pool walls. Just don't blow it up all the way—leave it about 60-70% full so it has some "give."
Putting on the winter cover
Now comes the part everyone hates: wrestling with the cover. It's much easier with two people, especially if it's even slightly breezy. Spread the cover over the pool and the air pillow, making sure it's centered.
Thread the wire cable through the grommets around the edge of the cover and use the winch to tighten it down under the top rail of the pool. If you live in a really windy area, those little plastic cover clips that snap onto the pool rail are a lifesaver. They keep the wind from getting under the cover and turning it into a giant sail.
A few final checks
Before you walk away and forget about the pool until spring, do a quick walk-around. * Is the filter drain plug in a safe spot? * Is the pump motor somewhere dry? * Is the cover tight enough that it won't flap?
Keep an eye on the cover throughout the winter. If too much water or heavy snow builds up on top, it can put a lot of stress on the pool walls. Using a small submersible cover pump to get rid of excess rainwater every now and then will save your pool frame a lot of strain.
Learning how to winterize above ground pool with sand filter equipment isn't exactly a fun Saturday, but it's the best way to make sure you aren't buying a new filter tank next year. Once you've done it a couple of times, it becomes a routine that takes maybe two hours tops. Then, you can head inside, grab a coffee, and ignore the backyard until the birds start chirping again.