How To Fix Foamy Hot Tub Water

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No matter how diligent you are about your hot tub water maintenance routine, there will come a time when you will have to deal with foamy hot tub water. And, unfortunately, when it comes to water maintenance, foamy water proves to be one of the most challenging issues of water quality to treat and prevent.

To better understand how to treat foamy water, you will need to look at the various causes of it, along with means of diagnosing, treating, and preventing it from returning. To begin with, we will take a look at a few of the reasons as to why your hot tub water becomes foamy to begin with.

What Causes Foamy Hot Tub Water?

Foaming hot tub water requires two components—a surfactant and air.

Surfactants are formed by molecules that work to reduce the water’s surface tension, which makes the mixing of oils and water easier. The combinations of these oils and water will then form a thin “skin” like substance on the water’s surface.

When the hot tub’s jets are then used, the air they create is trapped by the “skin.”  As a result, the greater the amount of air and surfactants present in your hot tub, the more bubbles will be produced and the longer they will last. Over time, those bubbles will gather in a group, and this build-up will then result in foam.

Common Causes of Foamy Hot Tub Water

The main reason so many hot tub owners have such a difficult time treating the appearance of foamy water is that no matter how much they try, to some degree, there will always be the presence of both surfactants and oils in the water itself. The best solution is proper maintenance and diligently keeping the amounts of the surfactants and oils below the point at which they will cause the foamy build-up.

Surfactants and oils will build up in your hot tub water for various reasons, and each reason will require its own unique treatment to fix it. With that said, keep in mind that foamy hot tub water is an easy fix, as long as you know the source creating it.

The most common causes of foamy hot tub water include:

  • Detergents and soaps
  • Lotions and oils
  • Build-up of biofilm
  • Waters balance is poor

Detergents and Soaps

Surfactants will commonly enter your hot tub water through the residue of detergents and soaps on your bathing suit or your skin. However, the most common method is that off your bathing suit.

Lotions and Oils

One of the most common ways that hot tubs develop foamy water is due to the build-up of lotions and oils. Each time you are in the hot tub, you expose the water to a variety of lotions and oils, including body oils, deodorant, body lotion, and beauty products such as makeup.

Although it is true that in small amounts, these substances will not present a negative effect on your hot tub water, however, over time, they will build up, typically on the surface of the water. If not treated, this build-up will then cause foam.


By its definition, biofilm is “any group of bacteria and other micro-organisms that stick themselves to a surface which is in regular contact with water.” If left untreated, the biofilm will stick to the hot tub’s surfaces, most usually the plumbing. Once the biofilm has attached itself to the plumbing, it will form a protective layer of slime and begin growing.

When the slimy protective layer has developed, chlorine and bromine sanitizers have a tough time battling it. The biofilm will continue to grow, and as it does, it will use more and more of any sanitizer you attempt to treat it with. You will then be left with less sanitizer to aid in breaking down any surfactants and other such substances that will cause the water to foam.

Balance Of The Water

Another commonly seen cause of foamy water is when it is poorly balanced and is low in calcium hardness. The balance of the water will not solely cause foamy water. However, water that is poorly balanced overall will reduce the tension on the water’s surface much in the same manner that surfactant build-up will, eventually causing over issues.

How To Diagnose Foamy Hot Tub Water

foamy hot tub waterFoamy water can have so many causes that it is often difficult to treat. However, the first step to effectively treating the problem is first to diagnose the cause. This process can best be achieved by taking a sample of your hot tub water to have it analyzed and tested by a professional. If there is an imbalance in your water, the chances are good that the issue lies in poor water balancing.

On the other hand, if the analysis shows that your water balance is fine, but the level of your sanitizers appears low, then biofilm build-up may be the issue. For this situation, you will want to add more sanitizer, and then on the following day, test your water. If the test shows that your sanitizer levels are once again low, then there is most likely a build-up of biofilm in your hot tub.

Lastly, if your water appears balanced and appears to have the proper level of sanitizer, the issue may lie in a build-up of lotions and oils. In most cases, a sign of this type of build-up will present with an oily “ring” around the inner walls of the hot tub at the surface level of the water.

If all else fails and an obvious answer is not obtained, the most likely answer is the build-up of surfactants.

How To Treat Foamy Hot Tub Water

Once you have successfully determined the cause of the foamy water in your hot tub, you will have a much easier time treating it.

There is a sequence of steps that will aid in treating foamy hot tub water. The first is to rebalance your hot tub water if it appears there is a need. If it seems the rebalancing has not done the job, then you will need to work to remove any lotion, oils, or soap build-up that may be the issue.

To achieve this removal, you can add an oil-absorbing sponge to the hot tub water. The sponge is designed to slowly absorb any lotions, oils, or soaps that may be present on the water’s surface. After a few days, you will see a decrease in the foam, and it will eventually stop. If you find that the foam doesn’t seem to subside entirely in a few weeks, you can add another sponge to help the process along. The last resort is to drain and refill your hot tub.

Finally, if a biofilm build-up is the culprit, you will need to drain and then clean the pipes of the hot tub to ensure the removal of the biofilm build-up.

How To Prevent Foamy Hot Tub Water

In a nutshell, the easiest way to prevent foamy water in your hot tub in the first place is to reduce the amount of lotions, oils, and soaps that the water is exposed to. The easiest manner in which to achieve this is to shower quickly before enjoying your hot tub so that any lingering makeup, deodorant, or other skincare products are removed from your skin.

Another step is to reduce the laundry detergent and fabric softener amounts that may be introduced to your hot tub water by thoroughly washing your bathing suit, using an extra cycle to rinse it before drying.

As a last resort, you have the option of using an enzyme-based chemical. Enzymes will naturally work to break down those non-living contaminants in your hot tub water, such as lotions, oils, and soaps. They are another option to reduce oil and surfactant build-up.


No matter how hard you try and work to prevent it, surfactants will and do build-up in your hot tub water. If your hot tub water appears to be already starting to appear a little foamy, you can try adding a small amount of anti-foaming chemicals on a weekly, regular basis. These chemicals will work to eliminate the foam until the hot tub is ready to refill. Contact Bliss Home Leisure today to help you with your foamy hot tub water.


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