Got A Problem With Hot Tub Foam? Here Are 3 Ways To Fix It



Hot tubs are all about the bubbles, but when the water chemistry gets out of hand you could find yourself fighting a foam epidemic.

We’re not talking about party foam that you’d find in an Ibiza nightclub, but rather, thick, frothy, foamy water that can put a damper on your time in the tub.

In this article, we’ll identify what hot tub foam is, why it’s there, and how you can get rid of it for good.

What Is Hot Tub Foam?

Hot tub foam is exactly what it sounds like. Some tubs have a small amount of foam, while others look like someone dumped a few cups of laundry detergent in the water.

In order for foam to develop, it requires three things: water, air, and surfactants. Surfactants are sticky molecules that reduce the surface tension of a liquid, making it easy for water to mix with oil.

You may have noticed how the ocean can get foamy at times. This foam works exactly the same way, with things like dissolved proteins, salts, and detergents acting as surfactants in the ocean.

Even when your water is taken care of properly, the tub will have some level of surfactants in it. If the hot tub chemistry gets out of balance, foamy water and potentially even scum lines can result.

Why Is Your Hot Tub Foamy?

Now that you know how foam is created, what are some of the reasons you might encounter this unwanted guest in your tub?

  • People using the tub. Face it, human beings are kind of disgusting. We shed hair and skin cells daily, and even our natural body oils pollute hot tubs. The more people use the tub, the dirtier it will get. Once it gets too dirty, the sanitizer in the water becomes ineffective until it is replenished, eventually leading to foam.
  • Body products. It’s not just our natural bodily secretions that pollute the tub. Bathers also bring in things such as body lotion, sunblock, makeup, shampoo, hairspray, and other personal care products. It’s for this reason you should shower before entering a hot tub, minimizing the amount of pollutants coming from your body.
  • Cleaning products. Swimsuits and swimming shorts can contain small traces of laundry detergent and fabric softener. This will ultimately seep into the hot tub water and increase the likelihood of foam occurring, which is why rinsing swimwear thoroughly after washing is recommended.
  • Drinking in the tub. Hot tub parties are quite popular, and many of these parties involve beverages of some kind. It’s quite easy for someone to accidentally knock a drink over, spilling the liquid into the water. This is another pollutant that can upset the hot tub chemistry and lead to a foamy mess.
  • Insufficient cleaning. Being a responsible hot tub owner means cleaning out your tub on a regular basis. The water should be tested, balanced, and shocked at least once a week, and even more frequently if the tub is seeing heavy use. Additionally, you should drain the tub every 3 months, scrub it down, and refill it so the water stays fresh. Failure to follow any of these golden rules of hot tub maintenance will definitely give you a foamy problem.
  • Cheap hot tub products. Invest in quality hot tub chemicals and products. It’s nice to save money, but if it’s going to lead to problems, it’s not worth the headache. The products you use in your tub are an investment. While some may be more expensive than others, it’s usually because they’re the better option. Just remember, you get what you pay for.

How To Fix Hot Tub Foam

There are a few ways to get rid of foam so it doesn’t spoil your next hot tub party.

Method #1: Use Anti-Foam (Temporary Fix)

All this method entails is adding an anti-foam chemical product to your hot tub. Almost instantly you’ll see the levels of foam disappear from the water.

This is a great option if you notice you have a foamy tub right before you want to use it. It’s also very affordable, with a 500 ml bottle costing under $20.

The downside is that this is only a temporary fix, and you’ll have to use one of the other methods to get the foam under control over the long term.

Here’s how to add it to your hot tub:

  1. Turn on the hot tub, allowing for the foam to build up. This will make it easy for you to see how much of it disappears once you add the product.
  2. You can either follow the dosing instructions on the bottle, or simply add a few drops of the product slowly until the foam disappears.
  3. Add in the product near the filter. This gives it the best chance to circulate throughout the tub.
  4. Walk around the tub and move the water around with your hand to further break up the foam.
  5. Turn the jets off to let the water settle and any remaining foam to dissolve.
  6. Turn the jets back on and use your tub.

Method #2: Rebalance Your Tub

Foam can be the result of improperly balanced water chemistry. This means you’ll need to test for pH, total alkalinity (TA), calcium hardness, and chlorine (or bromine).

Your pH level should be between 7.4 and 7.6, TA between 80 and 120 ppm, calcium hardness (CH) between 175 and 250 ppm, and chlorine between 1 and 3 ppm (bromine between 3 and 5 ppm). Low calcium in particular can be a cause of foam, so make sure your calcium levels fall in the proper range.

It’s also important to test for total dissolved solids (TDS) in the tub. TDS are everything that has been dissolved in the water – the surfactants we discussed earlier. For hot tubs, a TDS level under 1500 ppm is acceptable. If they’re over 1500, go directly to method #3.

By better understanding all of these levels, you’ll have a grasp on what water issues might be causing foam if you ever have another outbreak.

Here’s how to rebalance:

  1. Use test strips, a liquid test kit, or digital meter to test for pH, TA, CH, TDS, and sanitizer levels. Keep in mind that TDS may require specific test strips/kit, as it’s not a common testing parameter.
  2. Make adjustments to any of the levels that require it by adding the appropriate chemicals to the tub.
  3. Always practice proper safety when handling more volatile chemicals such as chlorine, to avoid accidents.
  4. After making adjustments, run the tub for about an hour so the chemicals can be mixed into the water.
  5. Retest the water and make any further adjustments.

Method #3: Drain And Refill

When hot tub foam becomes a problem, this is usually where you’ll end up in order to get rid of it for good.

Draining the tub should be done every 3 months to swap the water, but if you have a lot of foam and methods 1 and 2 aren’t cutting it, you’ll have no choice but to start fresh.

If you drain because of foam, it may be necessary to flush the lines and replace your filter cartridge. You should also wash the tub so that no surfactants remain on the tub shell. 

Here’s how to drain and refill your hot tub:

  1. Remove the filter cartridge and turn on the jets. Pour a line flush product into the filter housing. Dosages will vary, so follow the instructions on the bottle. Let it circulate for 15 to 30 minutes so it can clean out the lines. 
  2. Cut the power to the tub and drain it. You can either use a submersible pump with a hose attached to it, or attach a hose to the drain valve at the base of the tub. Be sure to empty the wastewater into an appropriate location like a sewer or storm drain.
  3. While the tub is draining (will take a few hours) clean your filter cartridge. If there isn’t much debris, a simple hosing down will do. But if the cartridge is really dirty, you may have to do a chemical soak, or replace the cartridge entirely.
  4. Once the tub is empty, wash it down. You can either use a spa cleaning product, or make a solution of 1 part vinegar to 4 parts water.
  5. Rinse the tub thoroughly. This means not once, not twice, but thrice! You don’t want to leave a trace of anything in the tub that can cause foam issues again.
  6. Replace the drain valve plug and fill up the tub using your outdoor water supply and a garden hose. For extra clean water, invest in a hose filter and install it in this line.
  7. Test and balance the water.
  8. Enjoy your clean tub.

How To Prevent Hot Tub Foam

Preventing hot tub foam isn’t rocket science, and you have a few ways to keep it out of your tub.

Basically, the more stuff that gets into water, the more likely it is you’ll have a foam problem.

Clean the tub regularly. This means stay on your weekly maintenance schedule and do drains every 3 months.

Take showers before you get into the water. This will remove a lot of pollutants from your body that can upset the water chemistry. You may also want to keep your hair out of the water, as shampoo residue or hair products can cause water problems.

If you’re partying, be mindful of having drinks near the tub where they can easily get knocked over. 

Finally, invest in high quality chemicals. Don’t skimp on your products just to save a few bucks. These products are usually inferior and will cause headaches down the road.

No Longer Foamy, Homie!

Hot tub foam isn’t aesthetically pleasing, but it’s relatively harmless. 

Still, you should strive to keep it out of your tub, and by keeping on top of your maintenance schedule, you can keep foam problems to a minimum.

Categories: Hot Tub Care, Hot Tub Problems