If you've just finished building a standard rectangular pool, choosing a 20 x 40 automatic pool cover is probably the next big decision on your list. It's one of those things that feels like a "nice-to-have" luxury until you actually own one, and then you realize you can't imagine living without it. A 20 x 40 pool is a decent size—it's roughly 800 square feet of water surface—and trying to manage that with a manual cover or, heaven forbid, no cover at all, is a recipe for a very long summer of skimming leaves.
When you're looking at a 20 x 40 automatic pool cover, you aren't just buying a piece of fabric to keep the dirt out. You're essentially investing in a safety device, a giant solar heater, and a way to slash your chemical bill all at once. Let's be honest: pool maintenance is the chore nobody tells you about when you're picking out tile colors. An automatic system takes a huge chunk of that work off your plate with the push of a button or the turn of a key.
Why the 20 x 40 Size is Such a Classic
The 20 x 40 pool is basically the "Goldilocks" of backyard swimming. It's large enough for the kids to have a proper game of Marco Polo, yet it doesn't take up so much space that your entire lawn disappears. Because this size is so common, finding a 20 x 40 automatic pool cover is usually pretty straightforward. You won't have to deal with the headaches of custom-shaping a cover for a "lagoon-style" pool that has twenty different curves.
Because the dimensions are standard, the tracks usually run perfectly parallel along the sides of the deck. This makes the mechanical operation a lot smoother. When the tracks are straight, there's less tension on the motor, which means your cover is going to last longer and run quieter. It's a clean look that fits the aesthetic of a modern, rectangular backyard perfectly.
Safety Is the Real Game Changer
If you have kids, pets, or even just neighbors with wandering toddlers, the safety aspect of a 20 x 40 automatic pool cover is probably your number one priority. Unlike a standard bubble cover (the blue ones that look like giant bubble wrap), an automatic safety cover is designed to hold weight. While nobody recommends walking on it for fun, most high-quality covers can support the weight of several adults in an emergency.
It provides a physical barrier that is far more reliable than a pool fence. Fences can have gates left ajar, or kids can find ways to climb over them. But when that cover is locked down over your 20 x 40 pool, the water is completely inaccessible. It's that "sleep better at night" kind of peace of mind. You don't have to constantly peek out the window to make sure the dog hasn't fallen in while chasing a squirrel.
Saving Money on Chemicals and Heat
It's easy to get sticker shock when you see the price of a 20 x 40 automatic pool cover, but you have to look at the long-term math. Water evaporation is the biggest thief in your backyard. When water evaporates, it takes your expensive pool chemicals and your heat with it.
On a 20 x 40 pool, you have a massive surface area exposed to the sun and wind. An automatic cover acts like a lid on a pot. By keeping the cover closed whenever you aren't swimming, you can reduce evaporation by up to 90%. This means you aren't constantly refilling the pool with the garden hose and re-balancing the pH every three days.
Also, if you use a pool heater, a 20 x 40 automatic pool cover is going to be your best friend. Heating 30,000 gallons of water is expensive. If you heat it during the day and leave it uncovered at night, you're basically throwing money into the dark sky. The cover traps that heat, often keeping the water 5 to 10 degrees warmer than an uncovered pool would be. You might even find yourself extending your swimming season by a few weeks in the spring and fall.
Choosing Your Installation Style
When you start shopping for a 20 x 40 automatic pool cover, you'll realize there are a few ways to actually put the thing on your pool. The most popular choice for new builds is a recessed track. This is where the tracks are tucked under the pool coping, and the motor and reel are hidden in a "pit" or bench at the end of the pool. When the cover is open, you can't even see it. It's sleek, it's hidden, and it looks incredibly high-end.
If your pool is already built and you didn't plan for a cover, don't worry. You can still get a 20 x 40 automatic pool cover using a "top track" system. The tracks are mounted directly onto your pool deck, and the mechanism sits in a housing at the end of the pool. While it's more visible than the recessed version, modern housings are designed to look like nice benches that you can actually sit on. It's a much easier retrofit than digging up your concrete to hide the tracks.
What About Maintenance?
I'll be the first to tell you that an automatic cover isn't "set it and forget it" forever. It's a machine, and machines need a little love. For a 20 x 40 automatic pool cover, the most important thing is keeping the tracks clean. A quick blast with a garden hose every couple of weeks to get the salt, sand, or dirt out of the tracks will save your motor from burning out.
You also need to keep an eye on the fabric. Most covers are made of heavy-duty reinforced vinyl. Over the years, the UV rays from the sun and the chlorine from the water will start to wear it down. You can usually expect the fabric to last anywhere from 7 to 10 years before it needs a "skin" replacement. The good news is that you don't usually have to replace the whole motorized system—just the fabric part.
Another pro-tip: never open the cover if there's a ton of standing water or heavy snow on top of it. A 20 x 40 automatic pool cover is strong, but trying to pull the weight of several hundred gallons of rainwater into the cover housing is a great way to snap a drive cable. Most systems come with a small pump that sits on top of the cover to drain the rain away. Use it!
Is It Worth the Investment?
To be perfectly honest, a 20 x 40 automatic pool cover is a significant investment. You're looking at several thousand dollars for the system and the installation. However, if you talk to anyone who has one, they'll tell you it's the best money they spent on their pool.
Think about the time you'll save. Instead of spending 20 minutes every morning skimming bugs and leaves, you just turn a key, and in 45 seconds, you have a crystal-clear pool ready for a swim. Plus, the safety factor alone is worth the price for many families.
At the end of the day, a pool is supposed to be about relaxation. Anything that reduces the "work" part of pool ownership and increases the "fun" part is a win in my book. If you've got the space for a 20 x 40, do yourself a favor and put a lid on it. You'll spend less time cleaning, less money on chemicals, and a lot more time actually floating on a raft with a cold drink in your hand.