Foam & Bubbles in the Hot Tub: What is the cause of them? - Sutro, Inc

Foam & Bubbles in the Hot Tub: What is the cause of them?

Foamy water in a hot tub can be caused by several different things, but the good news is that it’s easy to fix.

It’s important to differentiate between bubbles from the jets, foamy water, and brown scummy foam.

It’s normal for water to bubble and be opaque when the jets are running, but the water should be clear when the jets are off.

Foam can be either a white color or a brown color and will not disappear quickly when the jets are off.

It can also cause a scum line as well if the water quality is bad enough and it isn’t taken care of promptly.

What causes foam & bubbles in a hot tub

  • Detergents/soaps from clothes that weren’t fully rinsed
  • Shower and hair products that aren’t fully rinsed (especially if someone has long hair, it’s hard to rinse all of the products out)
  • Sunscreen, deodorant, lotions, and many other body or beauty products
  • Natural body oils
  • Biofilm
  • Improperly balanced water

How to get rid of foam & bubbles in a hot tub

The first place to start is to check your pool / hot tub chemicals, and balance water and shock to see if the tub maintains a good residual sanitizer level afterwards.


If it does, then keep an eye on levels going forward and the issue should be resolved.

If the foam remains it may be caused by a buildup of oils and/or soaps and you can add a hot tub sponge (there are several available on the market.)

If foam is still present then the next step is to treat the tub for biofilm.

Again, there are several products on the market that can be used. One of the most popular is “Ahh-some”.

Once the tub has been cleaned, drained, and the new water has been balanced then the issue should be resolved.

How to reduce foam & bubbles in a hot tub

  • Shower to rinse soap and body products off before using the tub
  • Do not use body products before getting in the tub
  • Keep water balanced and shock after each use
  • Use a filter cleaning product on the filter as it gets saturated with buildup over time and should be thoroughly cleaned to remove oils and other contaminants
  • Wash bathing suits separately, reduce the amount of laundry detergent used, and add an extra rinse cycle to help minimize the build up of detergent in the tub
  • Enzymes break down body oils and skincare products and will help reduce foaming and buildup. They are a natural way to get rid of foam in a hot tub.
  • If you want to know more, check more about hot tub and spas chemicals
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