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How to Get Rid of Foam in a Hot Tub

Matt Giovanisci, Founder and CEO of Swim University By Matt Giovanisci | January 8, 2024

How do you get rid of foam in a hot tub or swim spa? The fastest way is to use a Hot Tub Defoamer (Anti-Foam). This will quickly remove the foam so you can enjoy a soak. But it’s likely to come back and keep happening.

Hot Tub Anti-Foam

A quick relief to reduce foam in your hot tub. But not a complete remedy.

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In order to solve constant hot tub foaming, you need to understand what causes it to prevent it. Here’s a simple guide on how to get rid of hot tub foam. You can watch the quick video below or keep reading for a complete hot tub foam tutorial.

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What Causes Foamy Hot Tub Water?

Foam needs three things: water, air, and surfactants to appear. Surfactants are super-sticky molecules that reduce the surface tension, which makes it easier for substances like oil and water to mix. This makes the water viscous or “thick.” Think about adding cream to your coffee.

Your hot tub contains water and some surfactants, even if you properly maintain your hot tub chemistry. But if you slip a little on your maintenance schedule, you might flip on your jets and find yourself with a foamy mess. The more surfactants you have, the more bubbles (foam) you get.

A Hot Tub Full of Foam

The main foam-causing culprits in your hot tub are…

  1. Personal Care Products: Makeup, body lotions, and deodorant.
  2. Hair Products: shampoo, conditioner, and hairspray.
  3. Laundry Detergent and Soap: Yes, wash your swimsuits, but any leftover detergent in the fabric can really mess with your water’s chemical balance.
  4. Beverages: Spilling alcoholic or sugary beverages in your carefully tended water can lead to foaming.
  5. Human Bodies: The human body can produce oils, dead skin cells, and other waste. That’s why you have sanitizing chemicals in our hot tubs.
  6. Cheap Chemicals: They may not be as effective or as concentrated as more expensive options. Even worse, those cheap chemicals could actually cause a buildup of surfactants and a whole slew of other water chemistry problems.

If your sanitizing agents are overburdened with body oil and dead proteins, you’re probably going to have a bubble bath instead of a hot tub.

Can you test the hot tub water for surfactants?

Yes! You can buy test strips or a liquid test kit that tests for total dissolved solids (TDS). If you have a high TDS reading, you have high surfactants. However, this is not necessary to do if you drain and clean your hot tub every 3-4 months. Total dissolved solids are the result of “too much crap” in your water. That includes hot tub chemicals, oils, dead skin cells, etc.

Tip

The Best Way to Get Rid of Foam in a Hot Tub

While clearing a hot tub full of foam may seem like an impossible, messy task, it’s actually pretty simple.

1. Test Your Water

Before you do anything corrective, test your spa water to find out what your pH and alkalinity water balance. And your current sanitizer levels (chlorine or bromine). Knowing what your water chemistry looks like after foaming can help you understand how to avoid the problem in the future.

Another thing to note is low calcium hardness levels may cause foam in your hot tub. Low calcium means you have soft water. It can cause other problems, too, like corrosion and etching on your finishes. So, it’s important to regularly test these levels as well.

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2. Drain and Refill

Once you’ve tested your water and made note of all the chemical levels, the best thing you can do to get rid of the foam is to drain and clean your hot tub. If you have enough surfactants in your water to cause foaming, you may also need to do a line flush and replace your filters.

Since you need to drain your hot tub anyway, this is the perfect time to perform a hot tub deep clean as well.

Basic Steps to Drain Your Hot Tub:

  1. Use a line flush product, as needed, according to the package directions. This removes biofilm that builds up in your plumbing. This gunk is caused by lotions, cosmetics, and bodily waste.
  2. Remove the filters. Depending on how dirty they are, you can either clean them with a cartridge filter cleaner or replace them.
  3. Turn off the power to your hot tub, disconnect anything electrical, and trip the breaker.
  4. Drain your hot tub using a sump pump or the drain plug.

Draining a Hot Tub with a Sump Pump

Basic Steps to Clean and Refill Your Hot Tub:

  1. Once your hot tub is entirely drained, wipe down the interior surface with a mixture of one part white vinegar to four parts water. Or you can use hot tub cleaner.
  2. Thoroughly rinse the inside of your hot tub and wipe it down.
  3. Make sure to remove all traces of the cleaner. Otherwise, you’ll end up with foamy water again!
  4. Replace your hot tub filters.
  5. Refill your hot tub. I recommend you use a hose filter attached to your garden hose to prevent chemical impurities.

After you’ve drained, cleaned, and refilled your hot tub, test the water, add chemicals, and allow the water to circulate for at least a day. When the circulation is complete, test the water one more time to ensure it’s ready for soaking.

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For Quick Fixes: Anti-Foam Hot Tub Chemicals

Say you’ve got a party coming up and not enough time to go through all the steps to correct a foamy hot tub. You can buy a foam remover chemical, which will get rid of the foam in your hot tub almost instantly and can last for up to 24 hours.

Remember, foam remover chemicals do not address the cause of foam in your hot tub. It just relieves the problem for a little while. You’ll still need to drain and refill your hot tub to get rid of the foam for good.

Hot Tub Anti-Foam

A quick relief to reduce foam in your hot tub. But not a complete remedy.

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If you click this link and make a purchase, we earn a commission at no additional cost to you.

How to Prevent Hot Tub Foam

Frequently Asked Questions About Hot Tub Foam

I asked over 15,000 hot tub owners via email if they had any questions about getting rid of hot tub foams. These are the questions they asked, and here are my quick answers.

Is foam OK in a hot tub?

A little foam when jets are on is normal, but excessive foam indicates a water imbalance or contamination. It’s a sign to check your water chemistry.

Will shock get rid of foam in a hot tub?

Shocking can help if the foam is due to organic contaminants, but if it’s caused by soaps or oils, you might need to drain and refill your tub.

Will hot tub foam go away?

Foam will disappear if you correct the water imbalance or contamination causing it. Sometimes, a simple water change does the trick.

Does high pH cause foam?

Not directly, but high pH can lead to imbalances that make foam more likely. Balanced water is less foamy water.

Does baking soda reduce foam in hot tubs?

Baking soda won’t directly reduce foam. It’s used to raise alkalinity, which can indirectly help if low alkalinity is causing the foam.

Does vinegar get rid of foam in a hot tub?

Vinegar isn’t a go-to solution for hot tub foam. It’s more about balancing chemicals and cleaning out contaminants.

How often can you use a defoamer in a hot tub?

Use a defoamer as needed, but if you’re using it often, it’s time to check and correct your water chemistry.

Does too much chlorine cause foam in a hot tub?

Excess chlorine itself doesn’t usually cause foam. Foam is more often due to organic contaminants or imbalances in your water chemistry.

Need More Hot Tub Maintenance Help?

Matt Giovanisci, Founder and CEO of Swim University
Matt Giovanisci is the founder of Swim University® and has been in the pool and spa industry since 1993. 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.
Save Time And Money With Our FREE Hot Tub Cheat Sheet
Download this FREE printable cheat sheet to keep your hot tub clean and clear. You’ll never worry about your hot tub again with this easy-to-use guide.

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