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How to Clean Hot Tub Filters

By Matt Giovanisci | Updated: September 2, 2020

The longer hot tub filters go without being cleaned, the more likely it is you’re soaking in filthy water. So mark it on your calendar, set a reminder, and do whatever you need to do to make sure you’re cleaning those hot tub filters on a regular basis. And make sure you’re doing it properly and with the right materials.

Why You Need to Clean Hot Tub Filters

Hot tub filters are the things that help keep your spa water clean, but yes, it does get dirty. Very dirty, in fact. That’s because it’s collecting all those nasty contaminants and debris that would otherwise stay in the water.

They’re made to capture dirt, hair, and depending on the type of filter, even bacteria. It’s up to you to remove all that gunk on a regular basis. The dirtier filters get, the less dirt and debris they’ll pick up, which means what it doesn’t catch circulates back into the shell where you sit.

You can’t just pour a bunch of spa filter cleaner into the hot tub to circulate through the water. That would be convenient, but ineffective. The key to properly cleaning hot tub filters is understanding their structure.

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Hot Tub Filter Parts

Spa filters comprise three main parts.

  1. Media: Made from white, pleated spunbond polyester, the media is the part that actually cleans the water. As the water passes through the hot tub filter, the media catches the debris.
  2. Core: In order to stand up to the force of water flowing through it day after day, the media needs something to reinforce it. That’s the core. It’s usually a piece of tough plastic. Having a hard core in the middle of it also helps the filter perform better. If the filter were the media fabric alone, it would be moved by the water flow, and wouldn’t be able to capture as much debris.
  3. End Caps: Two plastic discs on either end of the filter keep the core and media in place. End caps also provide a way for hot tub filters to attach to spas’ filter chambers.

How to Clean Hot Tub Filters

Keep your cleaning supplies on hand so you’re always ready to clean the filters, both on your regular schedule, and if something should unexpectedly spill into the water. You’ll need:

Tip: Buy two sets of hot tub filters. While you’re cleaning one set, the other can be used in the hot tub.

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Weekly Hot Tub Filter Rinse

Remove the filters from your hot tub and give them a quick but thorough rinse with clean water. You can rinse them with a garden hose or in a large sink.

Be sure to spread apart each pleat and rinse well between them to get any dirt, hair, or other debris out. Allow the filter to dry before putting it back into the spa.

A weekly rinse will help keep debris from building up, and chemicals from eating away at the filter material. This will help the hot tub filters to work more efficiently and last longer.

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Monthly Hot Tub Filter Chemical Rinse

Generously spray the hot tub filters, and let them sit for about 15 minutes to allow the cleaner to do its job. Then rinse thoroughly with clean water.

If the filter cleaner you have doesn’t already come in a spray bottle, you can transfer it to a clean spray bottle. Check to see whether it’s a concentrate that must be diluted. If it is, dilute according to the manufacturer’s instructions.

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Quarterly Hot Tub Filter Chemical Soak (Every 3-4 Months)

Do this when you change your hot tub water, which you should also do every three to four months.

In a large, clean bucket, dilute the filter soak chemical with water according to the directions on the bottle. Make sure you use enough water to submerge one hot tub filter completely. If you have room, you can add more filters to the solution. If not, use one bucket per filter.

Place the filter in the bucket, and let it rest in the solution for 24 hours, or at least overnight. Then thoroughly finse the filter and allow it to air dry before placing it back in the hot tub.

Some pool and hot tub supply stores might offer this service, but it’s really easy to do yourself, and save some money.

Important: Whenever you use any kind of spa filter cleaner, make sure you rinse the filters completely before putting them back into the hot tub. Cleaning chemical residue can cause hot tub foam, and you’ll likely have to drain and refill your spa again.

5 Gallon Bucket with Lid

A 5-gallon bucket is very handy to have for mixing chemicals, soaking filters, or testing for leaks.

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3 Hot Tub Filter Cleaning Mistakes

Taking care of your filters helps them work more efficiently, but also helps them last longer so you don’t have to replace them as often. In addition to the correct cleaning process, you want to avoid a few things that could damage hot tub filters.

1. Never Use Bleach

While bleach can be effective for your hot tub shell, do not use it on your filter. Bleach is a harsh chemical—even when diluted—and it may damage the media fibers, greatly reducing the life of the filter.

2. Avoid Household Cleaners

If you’re trying to save money or just clean your hot tub naturally, you can use household cleaners on nearly every part—except hot tub filters. You could have a major foam problem in your spa, no matter how well you think you’ve rinsed the filter.

The hot tub filter cleaner is explicitly made for filter media. Stick with that.

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3. Don’t Use the Dishwasher

Sure, spa filters may fit in a dishwasher rack, and they’ll come out super clean. But you’ll also find yourself replacing your filter much sooner than necessary.

Dishwashing detergent is made for hard surfaces like ceramics and plastics, not filter media. It can damage the polyester fibers, reducing the filter’s effectiveness.

And no, you can’t put spa filter cleaner in your dishwasher. That’s asking for a whole other basket of trouble.

When to Replace Hot Tub Filters

Cleaning only does so much. After a while, spa filters wear out and can no longer effectively clean the water.

Plan to change spa filters at least once a year, more often if you use your spa often, and/or have a high bather load, which refers to how many people use your hot tub at any given time, and how often.

Dirty hot tub filters can even void your warranty, so it pays to check them once or twice a month. It’s time to replace your filters if:

You’ll be a lot happier, too, knowing your hot tub filter keeps the water you’re soaking in clean and free of contaminants and debris.

Happy Soaking!

Matt Giovanisci is the founder of Swim University® and has been in the pool and spa industry since 1995. Since then, his mission is to make pool and hot tub care easy for everyone. And each year, he continues to help more people with water chemistry, cleaning, and troubleshooting.
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