Why is my spa foaming? (How to Get Rid of Foam in Spa Water)

Foam in your spa water is a sign that something is out of balance. Plus, it's a nuisance when wanting to showcase your spa pool on a special occasion.

foam in a spa

In this article, we'll explain some of the main causes of foam in your spa pool or swim spa and some of the steps you can take to remove foam and prevent it from appearing!

We cover:

How do I get rid of foam in my spa water

To get rid of foam in your spa water, make sure your water pH and alkalinity are in the ideal range (7.2-7.8 for pH and 80 - 120 ppm for alkalinity.) You can also use an anti-foam product to help remove the foam. Cleaning your filters thoroughly can also help remove the foam. If none of these tips work, it’s time to empty your spa water and start again with fresh water.

Getting Rid of Foam in Your Spa Water

Foam in your spa pool calls for some overall maintenance. As soon as you turn your jets on and notice foam, follow this protocol to get it under control:

Watch: How to treat and prevent spa foam

Step 1: Check your pH and alkalinity

Before you change your spa pool water, make sure the pH and alkalinity aren’t the culprits. Using test strips designed for your chemical system, check the pH and alkalinity of the water. If levels are off, adjust both into an optimal range using a pH decreaser or alkalinity increaser. Need to learn more about balancing your spa water? Read our detailed blog titled: What is spa water alkalinity and pH.

Back to top

Step 2: Clean your filters

If your pH and alkalinity are balanced, make sure your filters are clean. Start by soaking your filters in a filter cartridge cleaner solution, and use a filter wand to hose them out thoroughly before fitting them back into the spa.

Step 3: Use an Anti-foam product

In the case that your water is balanced and your filters are clean, but you are still experiencing foam in your spa water, you can use a product called Anti Foam. This product instantly removes foam and temporarily stops the foam from forming.

It is worth noting that anti-foam products are a temporary fix that only treats the symptom and doesn’t permanently solve the problem.

Back to top

Step 4: Replace Your Spa Water

If you can’t seem to find another cause for the foam in your spa pool, it may be time to replace the water. Simply run a degreaser through your spa system, drain your spa, clean the inside of the shell and the filters thoroughly, and refill with fresh water.

Step 5: Shock the water in your spa pool

To keep foam at bay after you have refilled your spa pool, shock the water with a chlorine-free spa shock once a week. Add the recommended amount of spa shock into the water, turn the spa on and allow it to circulate for a day or so, or until the water tests safe. Spa shock helps break down contaminants and surfactants, helping to keep the water clear and foam-free.

Back to top

What Causes Excessive Foam in my Spa Pool?

Foam is caused by a build-up of surfactants, which, when combined with water and air, create bubbles. There are many surfactants that cause excessive foam in your spa, the most common ones include:

1. Detergent in the water

Detergents can get into your spa pool water when bathers get into the spa with freshly washed bathing suits harboring laundry detergent within the fabric. Many other body, hair, and clothing cleaning products can also contain detergents that may wash off upon entry into the water.

2. Oil build-up in the water

Over time, natural body oils inevitably build up in spa water, especially if bathers use the spa without showering first. Frequent use of your spa pool will speed up this oil build-up, along with getting into your spa with oil-based moisturizers or lotions on your skin. Some non-approved spa scents for spa aromatherapy may also contain oil. If you are using scents make sure they are an approved spa aromatherapy product and not oil-based.

3. Using cheap chemicals

Cheap chemicals contain more fillers and less active ingredients causing you to need more before seeing any results. These extra substances can over-saturate your spa water, contributing to foam.

4. Introduction of hair products, lotions & make-up

One of the most common causes of foam in a spa pool is the surfactants introduced by bathers such as hair products, lotions, and make-up. These beauty products wash off the bather into the spa pool water and build up over time, causing foam.

5. Total Dissolved Solids (TDS) Build-up

Total Dissolved Solids (TDS) refers to any organic matter, minerals, salts that may be present in your water. These may include calcium, magnesium, sodium, chloride among others. No matter how clean you keep your spa pool, after months of use, organic matter can build up and contribute to creating foam in your spa.

6. Incorrect pH and alkalinity

Testing the pH levels and alkalinity of your spa water with test strips designed for your chemical system is a key step to safe, longer-lasting spa water. Incorrect pH levels and alkalinity can cause foam, damage to your spa system, and cause skin irritation.

7. Your filter is dirty

If you clean your spa water without cleaning your filters, the surfactants and bacteria left behind in your filters can continue circulating in the water, causing foam.

8. You are using low calcium water

Water with low calcium levels (like rainwater) is softer with decreased surface tension allowing for more sudsing and causing foam to lather.

Back to top

What Chemicals Cause a Foamy Spa?

Surfactants are one of the key causes of foam in your spa pool. Surfactants are found in sunscreen, body lotions, fake tan, soap, and detergents.

In addition, drinks of any kind, not exclusive to alcoholic beverages, spilling in the spa water can affect your water chemistry, causing foam and other issues.

foam floating in a spa

Is Foam in Spa Water Bad?

If you have foam in your spa, it is simply a sign that the water is either overloaded with high TDS or is chemically out of balance. The foam in spa pools is not dangerous and is simply caused by the jets creating bubbles with the surfactants in the water. It is a common spa pool problem and means that your spa pool needs fresh water, or to be rebalanced in terms of pH, alkalinity, or calcium levels.

How to Diagnose Foamy Spa Water

Before you decide to drain and refill your spa pool, it is important to diagnose the water to pinpoint what is causing the foam. You can do this by considering how long it has been since you last changed your spa water, how frequently the spa is used, and whether the water is well balanced or not.

Start by testing the pH, alkalinity, and calcium levels of the water using test strips. If the water is well balanced and there is still foam, check your filters. If the filters are clean enough, consider the level of use of your spa pool. If it has been over 3-4 months since you last changed the water, and/or the spa has been in frequent use in those months, the foam is most likely caused by too much TDS or other surfactants in the water.

Back to top

Preventing Foamy Spa Water

Prevention is always key. Luckily there are many easy foam prevention tips that you can follow to keep the foam from forming on the surface of your spa.

Here are some simple foam prevention tips to keep your spa water clear and fresh:

  1. Avoid using lotions, moisturiser, sunscreen or other oils in your spa or on your body
  2. Shower before entering your spa pool
  3. Rinse your newly washed bathing suits in freshwater to get rid of detergents before wearing them in your spa pool
  4. If you have long hair, avoid submerging it in the spa water as long hair holds more product such as conditioner
  5. Test your water frequently and keep it in balance
  6. Keep your spa filters clean
  7. Replace your spa water every 3-4 months or after frequent use

If you are replacing your spa water after the 4 month period, run a pipe degreaser through your system before draining the water, soak your filters in an approved filter cleaner and refill with fresh water.

Frequently Asked Questions about foam in the spa

Can low pH cause foam in a spa?

Yes, low pH levels, below 7.2, can cause your spa pool to become highly acidic and interfere with your sanitizing chemicals. Unbalanced chemicals are known to cause foam in a spa pool.

Can high pH cause foam?

Yes, a high pH level is much more likely to directly cause foam than a low pH. Make sure to keep your pH levels around 7.2-7.8 to avoid foaming from your spa pool jets.

Will vinegar remove foam in a spa?

Yes, a common home remedy for spa pool foam is a 90:10 ratio mixture of vinegar and baking soda. You will need 20 litres (5 gallons) of this mixture for a 2000 litre (500 gallon) spa pool. Pour the mixture directly into the water to get rid of the foam.

What’s a natural de-foamer for spa pools or hot tubs?

A natural de-foamer, such as household vinegar, is a chemical-free alternative to chemical de-foamers. Pour household vinegar into your spa pool at a ratio of 1:10, vinegar-to-water, to temporarily get rid of spa pool foam.

How often should you shock a spa?

Spa pools in moderate to heavy use should be shocked weekly to keep contaminants at bay and leave your spa water sanitized and clear.

What causes spa pH to drop?

An increase in acidity will cause the pH levels to drop in your spa pool. Detergents, contaminants, and chemical imbalances can all contribute to lower pH levels.

Is foam in a spa bad?

Foam in your spa pool is not inherently bad, however, it is an indication that something is not right with your water. Either there is a chemical imbalance in your water, or the water is over-saturated with chemicals and Total dissolved solids (TDS).

How much foam is normal in my spa pool or swim spa?

A small amount of bubbles in your spa water is normal, especially while you have your jets on and water moving through the spa.

Back to top

Got more questions?

Talk to us on live chat, or email us your spa questions and we'll be happy to help!

Five Star Trust Pilot Rating

We are proud that Spa World customers have given us a Five Star Trustpilot rating.