What Causes Hot Tub Foam?

Foamy hot tub water.

It’s been a long day and you are dying for a dip in your hot tub. But after removing the cover, you discover a layer of foam on the top of the water. Can you hop in anyway?

Unfortunately, finding foam on your hot tub means a relaxing soak is out of the question.

What is Hot Tub Foam?

Hot tub foam is a common problem that occurs when water, air and surfactants — a scientific term referring to the compounds that lower surface tension between a liquid and a gas — collide. When the three meet, the surfactants form a barrier between the water and the air, resulting in foam.

Foam can occur in a few different forms. It can have a soapy look that covers the top of the water or it can be cloudy, making the surface of the water a murky white.

What Causes Hot Tub Foam?

The primary culprit of foam is failing to sanitize your hot tub water weekly or after heavy use, such as a hot tub party.

There are several sources for surfactant build up. The most common are:

Personal Care Products

Lotions, cleansers, makeup and even laundry detergent leave our bodies and swimsuits when we soak in water.

Chemical Imbalance

Foam will appear if the pH balance of your hot tub water is off. This is caused by using cheap chemicals or inaccurately mixing them. Water with low calcium or too much pH or alkaline can lead to cloudy water.

Regular Use

If you use your hot tub frequently, you yourself could be causing foam to appear. When you soak in your hot tub, you shed dead skin cells as well as oil from your skin. Both can throw off the balance of your spa’s water.

Food or Drink

If you snack or drink when you are in the hot tub, crumbs and spills will play havoc with your water balance. Keep beverages and food away from your spa to avoid unnecessary contamination.

How to Eliminate Foam

The simple answer is: hot tub chemicals. Start by testing your water to discover what it is lacking or overloaded with.

Sometimes, some extra bromine or chlorine will do the trick. If needed, use the appropriate chemicals to increase or decrease your spa’s pH. Always clean your hot tub filter as well to ensure you are rid of all contaminants. Failure to do so could keep the newly-added chemicals from doing their job.

If your water has not cleared within 24 hours, it is time to drain, clean and rinse your tub. When refilling your tub, using a hose filter can help to eliminate water impurities. Once refilled, test the water, add the necessary chemicals and allow the water to circulate for a good 24 hours before retesting. Once you receive a good test, you can resume use of your spa.

Vintage Hot Tubs

Need more tips on keeping your hot tub clean and uncontaminated? Vintage Hot Tubs, the oldest and most-experienced hot tub dealer on Vancouver Island, can help. We have been serving B.C. residents since 1978 and have the largest selection of hot tubs in the area. Our showrooms, located in Victoria and Langford, boast an extensive collection of hot tubs, hot tub covers and swim spas. Our experts are always on hand to answer any questions, from the warranty to the durability of a Covana hot tub cover.


Feel free to send us any questions or messages using the form below and we will get back to you very shortly!

Store Hours

Tues - Sat: 9 AM - 5 PM
Sun & Mon: Closed

Find Us Online