What causes hot tub foam and how to get rid of it

Updated on 11/04/2022 by Nathan Bull

There are many causes of hot tub foam, and because it’s often the result of more than one, it can sometimes seem hard to fix.


If you’re in a pinch and need an immediate but temporary fix, you can use a hot tub defoaming product to remove the foam quickly. A defoamer will only prolong the root issue, so you’re better off treating the underlying problem(s). Once you know what causes hot tub foam, it’s easier to figure out how to get rid of it long-term.


What causes hot tub foam?

Low or inconsistent sanitizer levels

Most foamy, cloudy, or discoloured water issues have to do in some way with low sanitizer (chlorine or bromine) levels. If your sanitizer levels aren’t maintained high enough, bacteria, algae and other organisms start to grow, and with it, hot tub foam is not far behind. When sanitizer levels are too low, it doesn’t take long for water issues to arise, and the longer they are, the more difficult it becomes to treat.


Keep your sanitizer levels between 3-5ppm for safe protection. If you experiment with anything lower, you’ll want to ensure you have and maintain a UV-C system like Jacuzzi ClearRay. You will also likely need to supplement your sanitizers with something like Spa Solution or a mineral sanitizer like Nature2 or Jacuzzi ProClear; if you choose to experiment with this route, make sure you keep your sanitizer at a minimum of 1ppm.


While low sanitizer is likely not the only reason for foamy water, it’s a must to treat when solving this problem. If you usually maintain your hot tub at 1-3ppm, bring it up to 3-5ppm until this problem is solved.


High total dissolved solids (TDS)

TDS measures the total amount of dissolved solids in your water - minerals, metals, salts, soap, lotion, body oils - pretty much anything that dissolves in your hot tub water. TDS is one of the primary reasons your hot tub needs to be drained every 2-4 months. When your hot tub has too many solids, you’ll get foam.


TDS should not measure more than 2000-3000ppm - you can test this using a TDS meter which you can find in hardware stores or on Amazon, or having your water tested by a local pool or hot tub store.


Soaps and detergents

Like a bath, when soap gets added to your hot tub, it creates foamy bubbles. Common sources of soaps and detergents are bathing suits, shampoos and cleaning agents. To help prevent this, rinse your bathing suit before entering the hot tub and if you have long hair, try keeping it above the water.


Oils and lotions

Hair conditioners, creams (hand and body), lotions, and oils (including body oils) contribute to the foam. Quickly rinsing off in the shower, especially after an intense workout, can help.



If your foam is oily and discoloured, your water feels slimy, or you have large white flakes, you’re probably dealing with biofilm, which you’ll want to address immediately. See our article on how to get rid of biofilm.


The best hot tub foam treatment

  1. Clean your filters. You may need to do this multiple times over a couple of days after letting your filtration system run for a few hours or overnight.
  2. Do a water test and balance your water, but don’t add your sanitizer (chlorine or bromine) just yet - just pay attention to it.
    Pro Tip: When water chemistry is out of balance, sanitizers won’t work effectively.
    • Sanitizers work less efficiently if pH is too high or low
    • Alkalinity stabilizes pH
    If your stabilizer level is above 60ppm, your sanitizer will become ineffective, and it’s time to drain and refill your hot tub.
  3. Shock your hot tub and run it for one full 20-minute cycle. Add your sanitizer. While you’re dealing with foam, you’ll want to keep your chlorine at or above 5ppm until it stops occurring when using the jets.
  4. Run your filtration system 24/7 until you are no longer experiencing foam. Consult your owner’s manual if your hot tub is not set to run filtration all day.


Optional: Add a Zorbie or clarifier to your hot tub to speed up the process.


If you can’t get rid of hot tub foam within three days using this method, you’ll likely need to drain and refill your hot tub.

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