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What Causes Foam in a Hot Tub? [7 Ways to How to Get Rid]

Hot tubbing is becoming a popular pastime in the UK, with affordable inflatables making the spa experience available to everyone, but looking after a hot tub can be a challenge, especially if you’re a newbie.

If you’re a hot tub owner, chances are you’ve noticed the foam that sometimes builds up on the water’s surface. While it’s not harmful, it can be unsightly and annoying. So what causes foam in a hot tub, and how can you get rid of it? 

Keep reading to find out!

How To Reduce Foam In Your Hot Tub

When the jets are on 

The easiest way to remove foam is to simply use a skimmer or your hands and scoop it out with the jets on full power. However, this won’t address the underlying cause of foam in the hot tub. 

Use an absorbing sponge – These can be bought cheaply online and work by simply absorbing any oil in the water and you should notice less hot tub foam in just a few days, 

Administer a shock treatment

You should shock weekly to keep your tub in optimum condition; however, if you notice a foam build-up, you should consider what can cause the foam to build up and start doing the shock more often. Shocking gets rid of harmful bacteria, breaks down organic waste and keeps your water clean and crystal clear. 

Shower before using the tub 

One of the best ways to stop your hot tub water from foaming is to shower before using the spa. This may seem a bit counter-productive, but it will prevent all sorts of oils from make-up, shampoo and moisturisers from taking up residence in your Jacuzzi.

Regular maintenance 

As we’ve already mentioned, taking care of a foamy hot tub is essential for your comfort, performance, and health. Set yourself a weekly routine, have plenty of hot tub water test strips on hand and address any issues immediately to prevent problems from occurring 

Use a hot tub foam remover.

The good news is that de-foaming products will instantly remove the foam from all hot tubs. However, they only solve the foam, not the underlying cause. 

Drain and refill

Perhaps the most effective way to banish foam is to completely drain and refill the hot tub and clean the spa filters or replace them. However, this is a big job, and some methods we’ve mentioned can be used until you’ve got the time to deep clean your inflatable hot tub.

The Natural Way To Get Rid Of Foam In Hot Tub

Vinegar is a natural de-foamer and can be used to prevent foam in a hot tub; however, with the advised ratio of 10.1 for a 200-gallon tub, you’d be looking at a lot of vinegar used and you’d probably get out the hot tub smelling like a bag of chips. 

How To Get Rid Of Foam in a Hot Tub Without Draining

Picture the scene you have a celebration planned, and everyone is looking forward to a hot tub party, but it’s full of foam! You don’t have time to drain the hot tub and clean it thoroughly, so what can you do? 

Causes of Foaming? 

Foam requires three things air, water and a surfactant; without getting too technical, surfactants reduce the water’s surface tension making it easier for it to combine with any oils present. 

This then produces a thin layer on the tub’s water surface and when air is added via the jets, it gets trapped beneath this “skin”, which causes bubbles. Eventually, the bubbles will converge, resulting in more of a bubble bath than a hot tub 

There are several reasons why your hot tub water becomes foamy and some may come as a surprise:

Beauty products 

When we enjoy a hot tub, the vast majority of us probably don’t think about the effects that our beauty products are having on the water. After all, these products are specially formulated to clean and condition our skin and hair, and it often seems like they should have little impact on the water in our spas. However, even seemingly harmless cosmetics like body lotions, makeup, body oils, sanitiser, soap, deodorant and conditioners can actually unbalance the chemical levels and cause the water in your hot tub to become foamy due to the amounts and buildup over time.

The reason for this lies in the chemicals found in most beauty products. These chemicals tend to be alkaline in nature, which means that they can cause some serious foaming when introduced into hot tub water. So if you want to avoid affecting the hot tub water balance and causing foamy water when you’re relaxing in your hot tub, make sure to shower beforehand. 

The PH balance is off.

Have you ever gone to jump into your hot tub only to find that the water is foamy and bubbly? While it might look like a giant bubble bath, this is a sign that something is off with your hot tub’s pH level. pH stands for “potential hydrogen” and measures how acidic or alkaline your hot tub water is. 

The ideal pH level for hot tubs is between 7.0 and 7.8. If the pH level gets too high or low, it can cause all sorts of problems, including making the water foamy. When the pH level is too high, it can cause calcium deposits to build up on surfaces, making them rough and scratchy. It can also irritate skin and eyes and make it difficult for chlorine to work effectively. So, if you notice that your hot tub water is starting to get foamy, it’s a good idea to test the pH level and make sure it’s in the ideal range. A simple test kit can help.

Soft water 

Many people believe that soft water is better than hard water, but in fact, soft water can cause lots of problems in a hot tub. While too much calcium can cause residue and stains, too little can result in corrosion, skin irritation and a foaming water problem. 

The total hardness should be between 150-250 ppm (parts per million). Using test strips and making the proper adjustments will ensure the water hardness stays in the optimum range.

If you are filling your hot tub for the first time and have a water softener, turn it off to prevent the water from foaming.

Regular use 

As we’ve touched on above, all sorts of things such as fabric softeners, creams and hair products can be the cause of hot tub foam building in your spa, so it stands to reason this will be increased the more the hot tub is used. 

A family of four using a hot tub almost every night is likely to encounter foamy spa water more than a couple enjoying a dip one or two times a week in a hot tub. 

Cheap chemicals 

Cleaning chemicals for hot tubs aren’t cheap and many people try to save money by purchasing more affordable alternatives. These products are cheap for a reason and are best avoided as they may contain less active ingredients. 

We would always recommend ordering your chemicals from a trusted brand. They may cost more initially but will be more economical in the long run as they’ll do a proper job. This page shares the spa chemicals we like.


Biofilm is a layer of micro-organisms that sticks to wet surfaces. It can’t be removed by rinsing alone and is challenging for either Chlorine or Bromine to tackle. This leaves less sanitiser to deal with surfactants and other substances that may result in hot tub foam developing. This page covers removing Biofilm from a hot tub in-depth.


How much foam is normal in a hot tub?

Can I add epsom salt to my hot tub? 

Is foam in a hot tub bad? 


With many people asking what causes hot tub foam? We hope this article helped answer that and if you’re experiencing hot tub spa foam, there are a few likely causes. It could be that you’re not cleaning it enough, that your beauty products are leaving residue in the water, or that the pH levels are too high. 

You can combat bubbles in a hot tub by showering before using hot tubs, adding the proper chemicals (not cheap alternatives), and regularly shocking the tub, especially after heavy use. 

There are plenty of products on the market designed to help reduce foam in your hot tub, from a foam remover, and absorbing sponges to a defoamer, but nothing beats regular maintenance

For more tips and advice on keeping your hot tub running smoothly, check out our other articles!

John Devlin

Hello, Welcome to my website. I’m John, and I created the InflatableHotTubGuide while researching these spas nearly a decade ago. Since its creation, the site has become the leading UK resource for many models. As a passionate hot tub user, I love to test and explore all the latest machines this industry keeps creating. I hope you find our content helpful.