What Causes Excessive Foam in a Hot Tub?

What Causes Excessive Foam in a Hot Tub lg

Who doesn’t love soaking in their hot tub at the end of a long day? But when you turn on the jets, it’s no fun to be bombarded with a ton of foam. So what causes excessive foam in a hot tub?

Here’s what I know, having owned 4 hot tubs over 15 years:

Excessive foam in a hot tub is caused by high levels of Total Dissolved Solids (TDS). This can come from body oils, lotions, and perfumes, or colognes. But it can also be caused by using a soap or detergent to clean your hot tub after draining if any residue is remaining on the acrylic shell.

To eliminate the foam, the water chemistry ought to be balanced, and the water drained and refilled every three months. The jets in your hot tub system naturally produce bubbles. These go away when you turn them off, but the foam will remain.

Read on to unpack the causes and their effects, stop foam formation, and totally get rid of the foam.

How do I stop my hot tub from foaming?

To avoid hot tub foam, ensure the water chemistry is balanced and that users of the tub adhere to the following before getting in: Shower, wear clean bathing suits and keep long hair tied back. They should also avoid eating and drinking in the hot tub and refrain from using tanning or suntan lotions.

Let’s look at each one.

Shower before entering the tub

There are some products you use daily or on a regular basis whose residues on your body make it highly likely that your tub would be foamy.

They include products such as:

  • Colognes/perfumes
  • Cosmetics
  • Deodorants
  • Shampoo/Conditioner
  • Hand and body lotion

In addition to this, there’s also dirt and sweat. So, it’s better to shower before entering the tub. If you only use these products sparingly or not at all, you may skip the shower.

Wear a clean bathing suit

Bathing suits often have residues of detergent on them.

It’s a no-brainer that this can trigger the formation of foam, especially if you use laundry detergents with perfumes and/or dyes. So, there’s a need to wash them very clean, rinse them well, and ensure they’re line-dried so that remnants of laundry detergent aren’t unwittingly taken into the tub.

At the very least, it’s a good idea to give them a quick rinse in the sink before putting them on.

Balance the water

Ensuring the right level of chemicals in your hot tub water is a vital and regular activity you’d need to carry out. It’s perhaps the most important way to prevent foam build-up. 

To this end, it’s good to make sure that you don’t skimp on buying high-quality chemicals and conducting regular tests. It’s smart to do some research so that you always get the best chemicals.

Ideally, you also want to use chlorine-free shock on a weekly basis.

Not sure what chemicals are the best? Check out my list of the top picks for hot tub chemicals in every category. Just CLICK HERE to see that list on my site.

Keep long hair tied back

Products used on hairs, such as shampoos, mousse, gels, and even strands of the hair itself, can find their way into the tub. So, it’s good to ensure that users with long hair tie it back well.

Some may want to wear shower caps and other types of caps that’d help reduce the possibility of the products and hair entering the tub.

Don’t eat in the tub

Don’t eat or drink in the tub seeing as remnants of the food or drink can lead to foam formation over time.

If you must eat, it’s good to eat and drink in such a way that fragments of the food don’t fall in and that you don’t accidentally spill the drink. Better still, you could get an accessory that floats on the tub and enables you to store food or drink.

In addition to the above, avoid skin-tanning lotions and remove any debris in the tub as both can lead to foam formation and ensure that the hot tub’s cover is opened regularly so that the tub can be exposed to more oxygen.

To learn about what causes hot tub foam, check out a recent article of mine where I did a deep dive into the issue. I explained that it’s a reflection of a chemical imbalance in your hot tub, but I shared the 1 sure-fire way to get rid of it without draining the hot tub.

Just click the link to read it on my site.

How do you get rid of foam in a hot tub naturally?

To eliminate hot tub foam, balance the water chemistry to ensure proper sanitizer and pH levels. Then, manually scoop out the excess foam with a net. Rinse off the filters with a kitchen sink sprayer and then put them back in. Run the jets and continue to scoop out any excess foam.

Proper water chemistry is a huge part of fixing this. So make sure to check:

  1. pH level
  2. Alkalinity level
  3. Sanitizer levels

Now, let’s look at some additional measures you can take to get rid of the foam naturally. 

  1. Add Vinegar and Baking Soda to the water at a ratio of 10:1. That’s a solution containing 90% vinegar and 10% baking soda. But note, this will raise alkalinity a little.
  2. You could simply drain the water, clean the tub thoroughly and refill it.
  3. Add a defoamer to the water. It’s a fast-action way to easily get rid of foam without affecting the water chemistry. We’ll check it out in more detail in a bit, but I like this one on Amazon for that job!

If everything has failed but you don’t want to drain it, the last-ditch effort before having to drain and refill is to hyper-chlorinate.

To do that you’ll add a double dose of chlorine-based hot tub shock. Leave the lid off and the jets on and let circulate 20 minutes. Continue to scoop off the excess foam on the surface of the water.

Also be aware that with super-high chlorine levels, you’ll likely have to wait a day or 2 before it will be safe to soak in. And make sure to check the levels before you get in.

What causes yellow foam in a hot tub?

Yellow hot tub foam can be caused by the presence of microorganisms and bacteria build-up, metals such as iron in high levels in the water, but it can also be triggered by low pH and high bromine levels.

It reflects that the tub is not in the most sanitary condition and that the water chemistry is out of balance. Even though yellow foam is not harmful to the users, it’s best not to use the tub until it’s restored to a better state.

So, how do you do that?

A good option is to clean the tub thoroughly after draining the water. Make sure the hot tub cover and the filters are also cleaned. Refill the tub and add sanitizers ensuring that the right quantity is applied.

And, as a preventive measure, you’ll want to shock the water a week after to reactivate the sanitizer level and to make the water less hospitable for the microorganisms and bacteria.

You’re probably curious about what makes hot tub water cloudy and smelly.

Find out the causes and the solution in a recent article of mine. I explained that high pH, low sanitizers, and algae build-up in the plumbing are often the key culprits. But there’s 1 sure-fire way to get smelly hot tub water and almost all of us do this daily!

Just click the link to read it on my site.

Is foam in a hot tub bad?

Foam in a hot tub is bad. While it’s not directly harmful to the users, it’s a sign that the water chemistry is not right and that there are contaminants in the water. Over time, it can lead to corrosion of some parts and the discoloring of the tub’s walls.

It’s not ideal that the tub is used in this state.

The contaminants are things like laundry detergent, sweat, body oil, shampoo, deodorant, makeup, and suntan lotion. Definitely, these are not substances you want in your water as you soak. 

If you’re thinking of taking a dip and the water’s foamy, you’ll have to wait and get rid of the foam first. 

Do you always have to drain the water and clean the tub each time it’s foamy? 

Not necessarily; it depends on how bad it is. If the water is foamy, smelly, and discolored, you’ll have to do a biofilm clean-out. There are other corrective measures if it’s not really serious. I’ll get into that in a bit.

But, on average, the biofilm clean-out is done when it’s a serious case. Then, you will want to drain and refill the tub every 3-5 months. 

I gave a range because it actually depends on a couple of factors which I explained in a recent article of mine. In it, I even shared how you can tell the ideal time to change the water simply by looking at it. 

Just click that link to read it on my site. 

How does hot tub defoamer work?

Hot tub defoamers work by pouring 1-3 ounces directly into the hot tub in the affected areas. They are fast-acting, as they work on direct contact with the foam. And the process of elimination is done without affecting the hot tub’s water chemistry. The water is safe to get in immediately following treatment.

The goal is to restore the water to a foam-free state. 

A key requirement in how defoamers work is partial solubility: they are half-in and half-out. If they’re too “in”, in other words, too soluble or dispersible, they may not work and may even aid in further foam buildup. 

If they’re too “out”, they may cling to the equipment’s surface and contribute to its defect. So, they are delicately formulated. 

They have “low-surface tension and spread rapidly at the gas-liquid interface to have an effective impact on the foam. They penetrate the foam and release the trapped gas enabling the foam to burst.

CLICK HERE to see my favorite on Amazon. 

It’s an eco-friendly defoamer that removes foam quickly. In fact, in minutes. And it doesn’t upset water chemistry. It’s made with silicone (it may not be ideal for you if you have a silicone allergy).

It’s highly concentrated, this is one of the reasons it gets the job done quickly, and it leaves no residue. It also leaves your sanitizers and other additives untouched. 

It’s got over 1,200 ratings on Amazon, and almost all are 5 stars.


Phew. That was a lot. 

The good thing is that with what we looked at, the days of having excessive foams are over. In the article, we looked at the causes of excessive foam. Essentially, it’s caused by chemical imbalance and contaminants (surfactants). 

We checked out simple steps to take to prevent foam buildup.

We learned about ways to get rid of foam naturally and that foams, while not really dangerous to users, show that the hot tub’s sanitary condition leaves a lot to be desired. 

We looked at what causes yellow foam, and we called it a day by checking out how defoamers work. I even suggested one of the best in the market. 

Photo which requires attribution:

foam by Martin Abegglen is licensed under CC2.0 and was cropped, edited, and had a text and graphic overlay added.

Jeff Campbell

Jeff Campbell is a husband, father, martial artist, budget-master, Disney-addict, musician, hot tub lover, and recovering foodie having spent over 2 decades as a leader for Whole Foods Market.

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