what causes foam in a hot tub

Quick Answer: The cause of foam in a hot tub is a result of specific water conditions and only develops once you turn on your hot tub jets. Usually, this foam is not damaging to you but is a sign that your hot tub has an unstable build-up of items in your water.

You see the foam rising as your hot tub bubbles forth. Is something wrong? Is it safe? Why is this happening?

Thankfully we know how to fix this issue and we are happy to show you what you need to do.

Where Does The Foam Come From?

Immediately when people think of foam they think of fizzy drinks and soap. Both can cause foam in your hot tub.

However, you should also be aware that other drinks, detergents, oils, deodorants, cosmetics, body products, and hair products can also cause a reaction in your water which then results in a foamy surface.

The other cause of the foam can be a low calcium level or unbalanced water. You should test your water regularly and check the calcium levels or else you will end up with what is called “soft water” which can cause foam but can also be damaging and corrosive to your hot tub.

If you notice that your water is starting to foam when you turn on the jets, you should immediately examine the water properties as the content may be unbalanced and could deteriorate rapidly. What may start as just some foamy bubbles can lead to horrible smells, hot tub damage, and even green water.

How Do You Get Rid Of Foam In A Hot Tub?

Now that you know that the foam should not be there, you need to know how to get rid of it. You might try scooping it up and separating the foam from the water but this won’t really solve your problem.

It would be similar to removing buckets of water from a sinking ship. It may look like you are making some progress but the source of the problem is still there.

Likewise, a quick fix that some people try is the varying types of anti-foam. But unfortunately despite some of their claims, they do not permanently remove the foam and it will likely be back within a day or two.

This can, however, be a great temporary solution when you don’t have time to test your water and treat it accordingly. For example, if you had a bunch of guests coming over in a few hour’s time, and you need your hot tub water to look normal for the evening, then anti-foam can be of great service.

For a longer-lasting solution, you should do is perform a water test. If you own a hot tub then you should already have a bunch of test strips to examine the alkaline, calcium, hardness, sanitizer, and ph levels. Make sure everything is at the amount it should be or adjust the quantities as needed until they are all completely correct. Try your best to test your water weekly.

Can You Prevent Your Hot Tub From Foaming?

Foam removal is not the same as preventing a foamy hot tub. It’s a good idea to know how to deal with the problem once it exists but far wiser to put a stop to it before it even starts becoming an issue.

Since a lot of the chemicals that encourage foam are from your body, your hair, and your face, make sure you shower before you use the hot tub. 

This will remove any excess oils, lotions, sanitizer, soap residue, etc. that could enter the water. The same should apply to any bathing suits used inside your bubbly spa. You should always rinse them with fresh water beforehand.

Additionally, since makeup and other hair products often remain on you even after a quick shower, try not to go underwater whilst in the hot tub. Keep your face and hair outside of the water.

We also know that foam is caused by many types of drinks and when they fall into the hot tub they can be a contributing factor towards the foamy water. With this knowledge, it would be a good idea to avoid taking drinks into the hot tub with you so you can avoid this risk altogether.

How Often Should You Drain Your Hot Tub?

Sometimes even after you test your water and perform all the maintenance needed, you still end up with a bubble bath full of hot tub foam. When this happens it may be time to drain and fill your tub with fresh water.

Many experts recommend draining your hot tub every 3-4 months, however, if the water is contaminated with chemicals that you cannot filter, then you may need to start from scratch and drain the entire hot tub.

We know this takes time but it is often the only solution. As you empty the water out, make sure you rinse the sides and bottom of the hot tub to get any excess oils, foam, soap residue, etc. washed away.

When you go to fill up the hot tub once more, make sure that you follow the foam prevention guidelines and that you treat the water so that it maintains the correct balance.

Are All Hot Tub Chemicals The Same?

Unfortunately, not all hot tub chemicals are equal. An additional possible cause of the foam in your hot tub can be cheap products. If the problem continues to resurface on a regular basis, check the brand of your chemicals and try switching them out for something of higher quality.

You get what you pay for and sometimes all you are purchasing is a bubbly problem. Check the reviews online for the products you are using and make sure that you are buying your hot tub chemicals from a trusted source.


Though having some foam in the hot can be normal you should never have an excess or buildup of foam. If you do, you need to treat/test the water, maintain the correct balance and adjust the hot tub chemicals as needed.

If this doesn’t work, try to drain and refill your hot tub.

Remember that an overabundance of foam is created by an imbalance in your water that is usually due to chemicals from your hair, face, body, or bathing suits and can also come from any other outside sources that you accidentally drop into the water.

Prevent the issue, test and change the water regularly and enjoy your perfect hot tub.

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