Foam in Hot Tub? How to fix the problem

Seeing foam form in your hot tub can be very annoying. However, foam in Hot Tub water is a common problem.Fortunately, it is often easy to eliminate, and you can help prevent its recurrence by understanding why it develops in the first place.

In this article, I will explore the causes of hot tub foam and the best methods to get rid of it and more importantly, to prevent it.

 

What Causes Foam in a Hot Tub?

If you’re dealing with foam in your hot tub, there are three possible causes:

1. Incorrect Calcium Hardness

If the calcium levels in your hot tub water are not balanced, foam can develop. Low calcium levels can also lead to internal damage, causing stains and deposits in the tub. Soft water is known to produce more bubbles and foam than hard water, so maintaining the correct water hardness is essential to prevent excessive foaming.

2. Incorrect pH Levels

If the water’s pH is too acidic or too alkaline, it can lead to various issues, including excessive foam. Regularly testing and adjusting pH levels ensures proper disinfection and helps prevent further complications. In some cases, simply correcting the pH can significantly reduce the foam problem.

3. Contaminants in the Water

Your hot tub water may appear clean, but it still collects residues from bathers, such as shampoos, lotions, and moisturizers. These products contain surfactants—compounds that can cause foam to form when air is introduced. Even small amounts of these contaminants can trigger foaming, making regular maintenance and water care essential.

 

How to Get Rid of Foam in a Hot Tub

There are several methods to eliminate foam from your hot tub. The first two focus on water maintenance, and you may notice that even a short lapse in regular upkeep can lead to foam and cloudy water. If foaming persists despite regular maintenance, it may be time for a complete water change.

1. Check Alkalinity and pH Levels

• Use a test strip to measure total alkalinity and pH.
• Dip the test strip in the water and compare the color against the provided chart.
• The ideal total alkalinity range is 100-120 parts per million (ppm).
• If alkalinity is too low, add an alkalinity enhancer; if too high, use a pH decreaser.
• Let the hot tub run for 30 to 60 minutes, then test again. Repeat adjustments if necessary.

2. Use a Clarifier or Anti-Foam

• Clarifiers help remove foam-causing particles by allowing the filter to trap them.
• Anti-foam can temporarily reduce foaming, but it does not solve the root problem.
• After adding a clarifier, run the hot tub jets for about an hour, then remove and thoroughly clean the filters.
• While some people use a clarifier to enhance water clarity, if foam and turbidity persist, draining and refilling the tub is the best long-term solution.

3. Drain, Clean, and Refill the Hot Tub

• If foaming continues, the best solution is a full drain, rinse, and refill.
• Hot tub water should typically be replaced every three months, depending on usage and maintenance.
• You can measure Total Dissolved Solids (TDS) to determine when a water change is needed.
• If TDS levels exceed 1,500 ppm, it is definitely time to replace the water.

 

How to Prevent Foam in a Hot Tub

Once foam develops in a hot tub, it can be difficult to eliminate. Prevention is always better than cure, and by following a few simple steps, you can reduce the risk of foam buildup and extend the time between full water changes.

1. Establish a Hot Tub Maintenance Schedule

• Regular maintenance is key to preventing foam.
• Follow a daily schedule that includes:
  • Checking alkalinity and pH levels.
  • Monitoring calcium hardness to maintain balanced water.
  • Ensuring disinfectant levels remain adequate.
  • Performing routine shock treatments to keep water clean.

2. Shower Before Entering the Hot Tub

• Encourage all bathers to shower before use to wash off lotions, oils, and other contaminants.
• This improves hygiene and reduces the introduction of surfactants that cause foam.

Final Thoughts

No one wants foam in their hot tub, as it often indicates an underlying issue. Foam is a sign of contaminated water, which can harbor bacteria. The best solution is to adjust water chemistry, boost disinfectant levels, or perform a shock treatment. Taking these steps will help ensure a clean, foam-free, and enjoyable hot tub experience.

 

Can I Help You?

If I can help you in any way I would love to hear from you. You can get in touch using the form below.

Thanks - Andi

 

Hi, Andi here. I own Buildahottub.com and also write all of the articles and info pages on the site. Some years back now, I built my own hot tub but struggled to find the information I needed. So, once my tub was complete, I started this website to help others in their own pursuit of hot tub and plunge pools DIY building information.

Fast forward to 2025, I've helped over 1400+ DIY customers just like you all over the world build hot tubs and pools. Have a good look around the site, there are lots of resources here. Please do get in touch if I can help you. - Cheers, Andi