You were just about to get into your hot tub to relax, and you open the lid to find all your dreams shattered: you’ve got hot tub foam. Hot tub foam, a mixture of water, air and surfactants (substances in the water that act like emulsifiers), can be a show stopper. It often occurs when your water is out of balance, does not have enough sanitizer, or has “too much stuff” in it (think skin cells, body salts, bacteria). The good news is that the problem is both solvable and preventable with easy, fast or long-term solutions (take your pick!).
Hot tub foam can be intimidating because there are many causes, and it can be hard to fix because hot tub foam is usually a result of more than one of those causes. This makes the process feel overwhelming, and any solutions appear to be magical. But the direct and straightforward method will produce the best results, and it needn’t be so complicated. Once you know what causes hot tub foam, you will likely figure out how to defeat it yourself (but don’t worry, we’ll cover solutions too).
Let’s look behind the curtain and expose the magician for the fraud they are! In order of the most-to-least likely culprits, let’s take a look at the causes of hot tub foam.
What causes hot tub foam?
Low or inconsistent Sanitizer Levels
Low sanitizer levels are definitely contributing to your hot tub foam. If your sanitizer levels are not maintained high enough to keep bacteria, algae, and other organisms from breeding, hot tub foam won’t be far behind. Sometimes it is a matter of trying to keep sanitizer levels to the bare minimum (1-3ppm). But, if those levels dip too low (even for an afternoon), it becomes more difficult to prevent water issues. Keep your sanitizer levels between 3-5ppm for foolproof protection and then (if you choose) experiment with 1-3ppm. To safely keep sanitizer levels that low, however, you’ll need to make sure you have (and maintain) a UV-C system. You will likely need to supplement your sanitizers with spa enzymes (our favourite tool) or mineral sanitizers.
While low sanitizer levels are not likely to be the sole cause of hot tub foam, you won’t ever defeat this sudsy monster without adequate sanitizer. Even if you usually can maintain your hot tub at 1-3ppm, until you’ve solved this problem, bring it up to 3-5ppm.
Soaps and detergents
If you want to turn your bath into a bubble bath, add soap; and if you want to turn your hot tub into a foamy hot tub, add soap. Common sources of soaps and detergents are bathing suits, residual shampoos, cleaning agents, and the neighbour’s ill-behaved prankster teenagers.
High total dissolved solids
When your water is tested by your local hot tub dealer, they can tell you how much “stuff” is suspended in the water. This is known as “total dissolved solids.” When there are too many solids in there, you get foam. It shouldn’t measure more than 2000-3000 ppm.
Oils and lotions
Hair conditioners, body and hand creams and other oils and lotions (not to mention natural body oils) are going to be contributing to your bubble party. Quickly rinsing off in the shower before jumping in the hot tub can help (especially after a workout or other sweaty activity).
In hot tubs, biofilm is a collection of bacterias that have organized themselves into microcolonies and created gooey protective layers around themselves. Hopefully, this is not the source of your bubbles because it is indicative of a lot of water issues.
The best hot tub foam treatment
The first step is to do a water test and balance your water. When your water chemistry is out of balance, your sanitizers will not work effectively. The super-simplified chemical chain is as follows: sanitizers work less efficiently if pH is too high or too low, and pH is too high or too low (or changes too frequently) because alkalinity stabilizes pH. Therefore, you must balance the alkalinity, before balancing the pH, before balancing the sanitizer in your hot tub.
If your chlorine or bromine is low, it is probably a contributing factor, and you will need to increase your sanitizer levels.
The second step is to clean or replace the filters. You may need to clean them a second (or third!) time after letting the hot tub filtration system run for a few hours or overnight.
The third step is to run your filtration system 24/7 until you are no longer experiencing foam. You will need to consult your owner’s manual if your hot tub is currently not set to run the filtration system all day long. If your hot tub uses a circulation pump, you can give the filtration system a boost by turning on your jet pump or activating the UV-C system (depending on the make and model).
To speed up the filtration process, you can use a hot tub clarifier, which will combine together particles suspended in the water for faster removal and throw in a Zorbie, which will absorb oils, lotions and more.
If you cannot get rid of hot tub foam within 3 days, you may need an in-store water test to check your total dissolved solids (or you can skip to the cure-all treatment below). Of course, you may want to solve hot tub foam immediately (albeit temporarily) with the quick treatment below that.
The guaranteed cure-all treatment to hot tub foam
You can guarantee a resolution to your hot tub foam by doing a water change and hot tub cleaning. If you have not drained and refilled your hot tub recently, this is probably a good idea (you should drain and fill your hot tub quarterly–although some owners do it less frequently without trouble).
Because you are experiencing hot tub foam, a simple drain-and-refill may not solve your problem for very long. Before you empty the hot tub, shock it to kill any bacteria or algae that may linger, and clean the plumbing with a hot tub cleaner to remove any biofilm and buildup (or use a rinse, though it may not be enough for hard-to-cure foam).
While the hot tub is empty, be sure to clean the surfaces with a non-abrasive safe hot tub surface cleaner.
The quick treatment
As fast as your dreams of relaxation evaporated when you found foam, you can get rid of it. Just squirt a little hot tub defoamer onto the bubbles, and they’ll disappear. But be warned: this is not a long-term solution. The next time you turn on your jets, they will most likely be back.
As they say, an ounce of prevention is worth a pound of cure; but in this case, it really is true. Hot tub foam is inconvenient and challenging to treat. Be sure to test your water chemistry weekly, use enough sanitizer, clean your filters regularly, maintain your UV-C system and shock your tub after every use to avoid this hot tub nightmare.
Reducing oils and lotions by rinsing-off in the shower before getting into the hot tub can help, and keeping soaps and detergents out of the tub by rinsing bathing suits after they are washed will also go a long way to preventing hot tub foam.
To make life easier: there are also many useful tools to vanquish foam from returning: