Hot Tub Foam: Standard Causes and Biofilm

There are a few undesirable elements that may show up in your hot tub from time to time, and a good example here is foam. While foam isn’t usually much of a risk in terms of health or skin concerns (it can be in very extreme situations, but isn’t usually), it’s often annoying to many homeowners and, perhaps more importantly, it can create a few issues with long-term hot tub maintenance or lifespan.

As top providers of custom gunite spas and other top hot tub materials, we at Packman’s Pools are here to assist many clients with these and related themes for upkeep and care of their spas. Why does foam sometimes collect in a hot tub, and what can be done to either prevent this from happening in the first place or to remove it once it’s present? This two-part blog series will cover the full picture.

hot tub foam causes

Standard Causes of Hot Tub Foam

In many cases, foam in the hot tub will be caused by standard interactions between the chemicals on your skin and the water itself. Here are some examples of this:

  • Body oils or lotions: When you enter the hot tub, your skin will of course bring with it any oils or lotions that were applied earlier in the day. In some cases, these can cause foaming when they mix with the water and other chemicals.
  • Detergents: If you happen to use any sort of detergent on your swimsuit or towel before getting in the hot tub, this can also sometimes lead to foaming (again, as a result of reactions with the other chemicals in the water).
  • Hair products: Similarly, any hair products that you use – shampoo, conditioner, hairspray, etc. – can cause foam to form when they come into contact with the water.
  • Perfumes or makeup: Perfumes and makeup can also sometimes lead to the formation of foam, as they often contain ingredients that can mix with the water in unique ways.
  • Drinks: If you happen to bring any drinks into the hot tub with you (a beer or cocktail, for example), the foam from these can also sometimes lead to an increased level of foaming in the water.
  • External factors: Finally, there are also a few external things that can cause hot tub foam. For example, if there’s a lot of wind blowing around outside and stirring up the water, this can sometimes lead to more foam being created. Likewise, if there’s a lot of dust or particulate matter in the air, this can also cause foam to form in the hot tub.


There’s another possible cause of hot tub foam that you should know about, however: Biofilm, which refers to bacteria or other microorganisms that stick to the surface of something (in this case, the surface of the hot tub). In some cases, biofilm can lead to foaming, as well as other problems like bad smells or skin irritation.

Not to fear, though: In part two of our series, we’ll go over basic remedies for these foaming causes, plus how to avoid them in the future. To learn more about this or any of our hot tub or swimming pool services, contact the experts at Packman’s Pools today.