Do you know how to clean a swimming pool? If you're a pool owner who's a little foggy on what to do and why it's important, allow this primer to fill you in—because while your pool might look sparkling-clean right now, it won't stay that way on its own. Pool maintenance requires vigilance and a firm understanding of a few scientific principles.
“There’s lots of chemistry that goes on in a swimming pool,” says Bill Carroll Jr., an adjunct professor of chemistry at Indiana University. “You’ve got to be careful about what you do and how you do it.”
Here's how to clean a swimming pool, and all the gross, gunky things that could be going on beneath that pristine blue surface that'll galvanize you to stay on top of this task.
What's in your swimming pool (if you really want to know)
When it comes to keeping a pool clean, “what you’re fighting is biological activity—human beings that go into the pool,” Carroll explains. “You might not, but the rest of the human population feels no compunction about peeing in a swimming pool.”
And it’s not just urine that contains germs that can funk up your pool. It’s also body oils, sweat, and other secretions.
Ready for another gross fact? A totally clean pool will not smell like chlorine, since chlorine gives off its signature odor only while interacting with biological substances. So if you catch a whiff, this means this chemical is battling urine or something else that's rolled off of, or out of, a human body, forming compounds known as “disinfection byproducts.” Yuck, right?
What is crypto?
Cryptosporidium, aka “crypto,” is a microscopic parasite found in fecal matter that, even in trace amounts, can end up in pools and lead anyone who swallows pool water to suffer from rampant diarrhea. (You're still reading, right?) Worst of all, regular chlorine levels aren't enough to get rid of it.
“This parasite has a really hard outer shell, so it’s hard to get disinfectant inside it to kill it,” says Carroll.
To ward off crypto, make sure everyone rinses off before hopping in the pool; you can also “hyperchlorinate" weekly, which is just what it sounds like: raising the chlorine levels temporarily to get rid of these little critters.
Why swimming pools turn green
Keeping the water clean is just the start. You should also brush down your pool's interior each week, says Mitch Brauzer, field support specialist of concept education/training for Pinch a Penny, a retail pool supply and service company.
"Weekly brushing prevents dirt and algae from clinging to the walls," he notes. “If a pool's interior is not brushed or an automatic pool cleaner isn’t run, algae will cling to the surface and the water will eventually turn green. It will take a lot of work to get the water clean and clear again.”
Another reason to brush or clean your pool regularly? To get rid of biofilm—a complex community of different microorganisms that will cling to watery surfaces much like plaque sticks to your teeth. Biofilm is bad news because it actually absorbs chlorine, rendering it helpless in killing germs and making it easier for other bacteria to set up shop.
The best pH for your pool
Another thing you'll want to watch is your pool's pH level. Ideally, it should remain from 7.4 to 7.6. Veer outside of that for too long, and it can reduce the life span of your pool by as much as 50%.
Specifically, a high pH can result in rough mineral and scale deposits on your plumbing. Meanwhile, low pH water can cause the inside of your pool and its equipment to deteriorate, says Mark Janes, COO and co-founder of ConnectedYard, a Hayward Industries company.
“Resurfacing your pool can also cost thousands," Janes cautions.
“It doesn’t take long to lose a pool,” warns Carroll. We're talking days, not weeks. “Maintaining it well is a lot better than trying to fix it afterwards," he adds.
How to clean a swimming pool
Whether you have a fiberglass, vinyl liner, or concrete pool, you'll need core supplies to do your weekly cleaning. These include the following:
Nylon pool brush: To keep algae at bay.
Skimmer: Because no one likes to doggy paddle through June bugs.
Chlorine: Essentially, the chlorine you use to disinfect your pool is a stable solution of bleach. (Just don’t try to pour laundry bleach into your water. You’d have to add lots of bottles to get the level of disinfectant that you need.)
Shock: This form of unstabilized chlorine, good for weekly sanitizing, is more potent. “It very quickly elevates the amount of disinfectant in water and quickly kills things there,” says Carroll.
Water test kit: This is to check the pH. “If you don’t balance your pool water weekly, the walls and equipment will start to degrade over time and may shorten the life of pumps, motors, and filters," says Brauzer.
Chemicals (and gadgets) to balance your water: In addition to keeping your pool's pH at 7.4 to 7.6, the proper alkalinity (about 100 to 150 parts per million) will help your pH stay stable.
Many pool owners find balancing their pools to be particularly challenging, says Janes. If that’s you, think about smart water care. For instance, the floating pHin smart monitor checks your water chemistry 24/7. An app notifies you when to add chemicals, what you need, and how much.
If you're not feeling up to the task, hire a pool pro. That way you can spend more time enjoying your pool and less time struggling to keep it afloat.