Does Your Swim Spa Look Like a Giant Bubble Bath?

Ok, but even if you have enough foam to make a beard and moustache, it’s time to learn why you get foam in your swim spa, how to get rid of it and prevent it.

Foamy water is common for many swim spa owners. No worries, FROG®, the water care expert, is here to help!

Foamy Water Causes

Foam happens when your swim spa’s water collides with air and surfactants. Surfactants are compounds that lower the surface tension between a liquid and a gas.

When surfactants – water and air interact – a barrier forms between the water and air, resulting in swim spa foam.

A shot of white, bubbly and foamy swim spa water

As the amount of surfactants in your swim spa increases, so does bubble formation. As bubbles accumulate, they combine with each other and create foam. That fun looking foam water plus air is contaminated with chemicals or solids.

What Causes Surfactant Buildup?

You may be surprised. Some common things cause surfactant buildup, and some you may not even know about.

Once you know, you can manage them:

Various personal care products lay on an orange background

Oils and Lotions

Oils and lotions in the water are the most common causes of foamy swim spa water. And they come from you!

Body oils, deodorant, beauty products and body lotion can add a variety of surfactants to the water.

It’s the buildup over time that causes foam. If the buildup isn’t treated, the surfactants these products add to the water lead to more and more foam.

That’s when you end up with a giant bubble bath!

Detergents and Soap

Detergent and soap residue on your bathing suits and skin inevitably get into your swim spa water when you get into your swim spa. These residues can cause foamy water.

We recommend a dedicated swimsuit to use in your swim spa – one that you don’t wash with detergent. After soaking in the swim spa, give your swimsuit a good rinse and hang it to dry.

It’s also a good practice to rinse off with water – no soap – before entering your swim spa to get as much soap, oil and lotion residue off your skin as possible.


Biofilm is a slimy and sticky microbial colony made up of different types of microorganisms including bacteria and algae.

These microbial growths attach themselves to swim spa surfaces. Biofilm develops when your swim spa water is not properly treated or maintained.

Biofilm can lead to foamy water because the bacteria within it produces surfactants as a byproduct of their metabolic processes.

Poor Water Balance

On it’s own, poor water balance, which means that Free Chlorine, Total Alkalinity, pH  and Total Hardness are not within ideal levels, won’t cause foamy water. But poor water balance, especially low Total Hardness (also called calcium hardness), lowers the surface tension of water in the same way that surfactants do.

When the water’s surface tension is lower, it is easier for it to combine with air, causing foam.

A woman's hand compares her FROG @ease test strip results with the bottle. In the background is swim spa water

Foamy Water Solutions

Now that you know what causes foamy swim spa water, here’s how to solve it:

1. Balance Your Swim Spa Water

Even when it’s obvious that you have foamy swim spa water, it’s always best to start with balancing your water. Then you’ll know what needs adjusting.

Every time you balance your water, check these levels, and correct as needed and in this order:

  • Total Alkalinity: 80 – 120 ppm

  • pH: 7.2 – 7.6

  • Total Hardness: 150 – 250 ppm

Want more details on water balancing? Download the FROG Water Balancing Guide for Swim Spas here.

2. Shock the Swim Spa

If balancing the water didn’t get rid of the foam, the next step is to shock your swim spa water.

Swim spa shock oxidizes your swim spa’s water and reactivates your swim spa’s sanitizer. This oxidization helps break down surfactants and ultimately gets rid of foam.

A packet of FROG Maintain sits outside a box full of the product.

FROG Maintain® for Swim Spas is a non-chlorine shock that works in 15 minutes. It’s cyanuric acid-free, so it won’t contribute to cyanuric acid buildup in swim spa water. Plus, it comes in a one dose cut-and-pour packet, so there’s no measuring and no mess. It’s easy!

3. Remove Oil, Lotion, Detergent and Soap Buildup

If water balancing and shocking the water didn’t help get rid of foam, it’s time to remove any buildup from products that swim spa users have introduced to the water.

How? Add a scum absorber to the water! You’ll find numerous types of scum absorbers from sponges in fun shapes to scum balls. Check them out at your local retailer.

Once you put a scum absorber into the swim spa water, it will take a couple of days to fully absorb the scum.

However, you can speed up the process by adding multiple scum absorbers to the water. The foam should now decrease unless it’s caused by biofilm.

4. If Your Swim Spa has Biofilm – Follow these Steps:

First: Drain the swim spa. If absorbing the scum didn’t solve the problem, your swim spa foam is most likely due to biofilm buildup.

The only way to get rid of foam caused by biofilm buildup is to drain your swim spa and thoroughly clean the filter, surfaces and pipes, rinse, refill with fresh water, balance the water and add sanitizer.

An overhead shot of foamy swim spa water

Check with your local retailer for a spa purge product and follow the manufacturer’s instructions when using a new product in your swim spa care routine.

Second: When the water has been drained, clean every surface of the swim spa with cleaner your retailer recommends.

Clean hot tub pillows, rails, the water line, inside and around the jets, rails, steps, the sides, and surface of the hot tub to remove any persistent biofilm. Leave no surface behind!

Third: Rinse

After cleaning your swim spa, thoroughly rinse it to ensure all the biofilm is gone – otherwise foam will return.

Fourth: Refill the spa with fresh water.

Important Tip: Put a hose filter on your hose when you fill your swim spa to avoid other damaging chemicals from entering the fresh water.

Fifth: After refilling, balance the water.

Sixth: Once the water is balanced, add your swim spa sanitizer.

an overhead shot of a sparkling swim spa with a FROG @ease for Swim Spas floating in the water

Water Care Expert Tip: Any type of defoamer or “anti-foam” product is only a short-term fix; it will remove the foam from the water temporarily.

If you use an anti-foam product but don’t treat the cause of the foam, the foam will return once the chemical has been used up.

Foam is stubborn and best treated by the steps outlined above!

Once you’ve rid your swim spa of foamy water, you’ll want to prevent it.

5 Steps to Prevent Foamy Water

A pair of man's hands rest on the edge of a swim spa as they fill it with a green garden hose

1. Drain and Refill Your Swim Spa Regularly

Since foamy water is typically caused by  a number of things – usually a combination – including personal care products, chemical imbalance, heavy use, food or beverages spilled in the water, or biofilm, it’s best to drain and refill your swim spa water regularly.

You’ll find many different recommendations on how often to drain your swim spa water, typically anytime from 2 to 3 months.

However, those who use FROG® products to sanitize their swim spa can usually increase the time between draining and refilling if they replace the chlorine cartridge as needed, and the FROG Mineral Cartridge every 4 months.

When you drain and refill your swim spa, consider it a refresh as it will get rid of dissolved solids that have accumulated in the water from swim spa use.

After cleaning and refilling your swim spa, balance the water before adding the sanitizer. Yes, balancing the water is one of the key parts to keeping the water clean, clear and ready when you are!

Test your swim spa and adjust as needed to keep it within ideal water levels:

Free Chlorine: 2.0 – 4.0 ppm

Total Alkalinity: 80 – 100 ppm

pH: 7.2 – 7.6 ppm

Total Hardness: 150 -250 ppm

2. Use a Non-Chlorine Shock Weekly

Use a chlorine-free shock weekly to prevent foamy swim spa water. Shocking the water helps break down oils and lotions or soap and detergent. If you use your swim spa frequently, more than 3 times a week, it’s a great idea to get on a consistent shocking schedule.

We recommend using FROG Maintain® for Swim Spas – it’s one dose in one single easy-to-pour pouch. Non-chlorine shock also means you get clean water without any Cyanuric Acid.  Added bonus, when you use FROG® @ease® for Swim Spas, you shock only once a month – not weekly!

A FROG @ease for Swim Spas System sits in front of a packet of FROG Maintain for Swim Spas

3. Routinely Clean Your Filter

Clean your swim spa filter at least once a month. There’s an array of products to choose from, including those to soak the filter in overnight. These cleaners remove all dirt, grease, soap and oil buildup from the filter cartridge.

Check the directions on your swim spa manual for best tips to clean the filter and ask your local retailer for filter cleaning products and tips.

Water Care Expert Tip: Have a clean filter cartridge ready to go to use while the “dirty” one is soaking, then you’ll avoid the wait, and always have a fresh filter when needed.

Cleaning your filter regularly not only helps you avoid swim spa problems, but also helps extend your filter cartridge’s life. Avoiding trouble is better than fixing it!

4. Rinse Off Before You Use the Swim Spa

Take a quick shower without soap before you use the swim spa. This helps prevent personal care products you may not even realize are on your skin or swimsuit from entering the swim spa water and disrupting the chemistry.

Your favorite lotion, perfume, deodorant, or sweat from the day, pollen and all kinds of “things” can be rinsed off with just plain water – no soap – and kept out of your swim spa water.

Photo of an orange one piece swimsuit

5. Have a Dedicated Swimsuit for Swim Spa Time

Bathing suits that have been washed with typical laundry soap are filled with detergent. Yes, even if you rinse them, soap residue sticks around.

We recommend you choose a swimsuit to use in your swim spa that is not washed with soap or detergent. Only rinse your selected suit with plain water and let it dry between uses. This helps prevent surfactant buildup, and therefore, helps prevent foam!

The Foam Finale

Ultimately, foamy swim spa water can be an inconvenience for swim spa owners. Foamy water means its thick and old or contaminated with chemicals or solids – who wants to soak or swim in that?

But with a little knowledge and proper maintenance, you can easily get rid of and prevent it.

Now you know the various causes of foamy water, including the presence of oils, lotions, detergents, soap residues and biofilm development.

Most importantly, you know how to get rid of the foam.

Put our preventive strategies to work and follow a consistent water care routine, so you can enjoy a crystal-clear and foam free swim spa experience every time.

A woman in a one piece swimsuit swims in a Bullfrog swim spa.

If you need help along the way, check out the FROG Water Care App, your local retailer, or call our Customer Service Department at 800-222-0169 Mon-Fri 8-5 Central or email us at


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