Why is My Hot Tub Water Foaming?

Ever opened your spa cover and found your hot tub is foamy? This is a common issue, and it can be challenging to treat and prevent it effectively. In this guide, you will discover what causes hot tub water to foam, how to diagnose, address it and ensure the problem doesn’t reoccur.

What Is Hot Tub Foam?

Hot tub foam occurs when surfactants, air, and water meet. A surfactant is a compound that minimizes surface tension between a gas and a liquid. When the three collide, a barrier forms occurs, causing foaming.

Foam can happen in various forms, including a soapy appearance, covering the water top, or a murky white appearance on the water surface due to cloudy foam.

What Causes Hot Tub Water to Foam?

Surfactant build-up is the primary reason your hot tub is foamy. Bubbles occur when this compound combines with air and water. Surfactants resulting in foamy water include:


They can get into your hot tub when bathers enter with bathing suits containing detergents.

Oil build-up

No matter how you maintain your spa, natural body oils will accumulate in the water over time. Showering before using the hot tub can minimize oil build-up.

Total Dissolved Solids (TDS) Accumulation

These are salts, minerals, and any organic matter present in the hot tub water. They include chloride, sodium, magnesium, and calcium.

Incorrect alkalinity and pH

Correct alkalinity and pH levels are essential for spa water safety. If they are not appropriate, you risk skin irritation, spa system damage, and foaming.

Dirty Filters

Without regular filter cleaning, bacteria and surfactants will circulate in the spa water and cause foam over time.

Inappropriate Chemicals

Less active chemicals require excessive use for optimal results. When they over-saturate in the water, foaming occurs.

How to Get Rid of Foam

If your hot tub water foams, there are several steps to address the issue, including:

Use anti-foam products

This is the first step to eliminating foam from your hot tub water. While it does not address the primary cause, it gets rid of the foam and destroys algae.

Rinse filters

Cleaning your filters will remove grime and dirt from the hot tub water. Filter rinsing is a vital part of spa maintenance


Enter the hot tub with clean bathing suits

Cleaning and rinsing your bathing suits before getting to your hot tub will reduce detergent build-up and slow foam creation.

Use quality chemicals

While you may want to save money when purchasing chemicals, investing in cheap products can cause more problems.

Regular water testing

With hardness test strips, evaluate your hot tub’s water pH level at least once a week. If you notice an imbalance, use a pH shock.

Empty the hot tub

If the suggested methods fail, you could empty your hot tub as a last resort. Use a pipe flush to drain and fill it with fresh water. Sometimes, this may be the best option, especially after an extended use.

Engage Maintenance Professionals

Proper pool and hot tub water maintenance can give you the best experience and ensure you don’t struggle with issues like foam. Contact hot experts today for help if you need assistance or more information.

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