Hot Tub Foam: The Easy Guide to Getting Rid of it

Having foam in your hot tub water is a common problem. If you are lucky, it’s not too difficult to get rid of hot tub foam and, with a basic understanding of why the foam formed in your hot tub in the first place,  you can help prevent it forming again.

In this post we will have a look at what the causes of hot tub foam are. We will also check that you definately have a foam problem before going on to look at the different ways that you can try to fix the problem. Prevention is always better than cure so we will finish by checking out some top tips for preventing hot tub foam from forming in the first place.

Let’s start by having a look at what causes hot tub foam in the first place.

What causes hot tub foam?

If you have a foam problem in your hot tub then there are three possible causes:

Incorrect calcium hardness levels – If the calcium levels are incorrect in your hot tub water this can cause foam to form. An incorrect calcium level can also be problematic in that it can cause damage to the internal parts of the hot tub, as well as causing staining and leaving deposits.  Soft water is well known for causing bubbles and foam to form more than hard water so it’s important that the hardness level of the water is correct to prevent exess foam forming.

Incorrect ph levels – If your water has the incorrect pH level and is either too acid or too alkaline this can cause lots of problems including causing excess foam.  It’s important that you check your pH levels on a regular basis and adjust as necessary to keep your sanitizer working well and also to prevent other problems. Sometimes just correcting the ph level of the water will cause the foam problem to subside.

Dirty hot tub water – Your hot tub water doesn’t need to actually look dirty to start causing a bit of a foam problem.  Inevitably, your water will collect all sorts of debris, particularly from bather’s bodies, such as shampoos, lotions and moisturizers etc. These lotions and potions all contain molecules called surfactants which are the cause of the foam problem. The surfactants will happily sit in the water probably unnoticed until air is introduced into the equation and it’s then that the foam problems begin.

Surfactant molecules make it easier for chemicals like oil and water to mix and reduce the surface tension of water.  The surfactant molecules are attracted to water at one end and repel water at the other. When air is included in the mixture,  for example when you are splashing around in your hot tub or the jets are on, the surfactant molecules arrange themselves on the border between the air and water.  Because they are repellent to water at one end only, they force the water molecules into a round bubble-like shape once they start stacking on top of each other.

Have you definately got a foam problem?

Before we start looking at the ways to get rid of the foam let’s make sure that you do actually have a phone problem in the first place!  Remember that when the hot tub jets are on, the water will get very bubbly anyway. In fact, some more sophisticated hot tub manufacturers include systems that increase the amount of bubbles deliberately.   To check whether or not you have a real foam problem switch the hot tub jets off and then wait for a good minute or so. If you still have bubbles or foam after a minute then you probably do have a problem.  The bubbles will probably be relatively large and a bit sticky to the touch.

To a certain extent all hot tubs will have a little bit of foam sometimes and this need not be a massive problem.  However, whenever the foam starts to build up or clump together then it really is time to start addressing the issue.  Not only does it look unpleasant but the foam can also harbor harmful bacteria that can easily be passed on to bathers.

How to get rid of hot tub foam

Once you have definitely got foam in your hot tub there are a number of things that you can try to get rid of it. All of these are water maintenance related and you will find that, even if you forget to carry out your routine maintenance for a short while, you risk foam and cloudy water build-up in your hot tub. It’s also possible that you will get foam even if you do keep up with your water maintenance and foamy water in this instance most likely means that you are ready for a complete water change.

Let’s have a look at how to get rid of foam from your hot tub step by step. We will start off with the easiest possible solutionss and work our way through from there.  Hopefully your foam problem will be solved by the first two or three points on the list but if not, carry on working your way down the list until you have solved the problem.

Check total alkalinity and PH levels –  The first thing to do is to get a test strip and test your total alkalinity and pH levels. Simply dip the test strip into the hot tub water and then check the color with the color chart on the test strip pot.  The total alkalinity of the hot tub water should be between 100 and 120 parts per million.

If you need to raise the alkalinity then use a hot tub alkalinity increaser. If you need to lower the alkalinity then use a hot tub PH decreaser. You will need to know how many gallons of water your hot tub holds so that you can work out how much balancing chemical to add.  Check on the balancing chemical’s container for the right quantity and then scatter the chemical over the hot tub water with the jets running. Leave the hot tub running for between 30 and 60 minutes and then re-test and adjust again if necessary.

Next, test the pH level.  You should have a Ph level of between 7.4 and 7.6.  Again, add balancing chemicals if you need to correct. If you need to raise the PH then add a hot tub PH increaser. If you need to lower the PH use a hot tub PH decreaser. As you did before when you were testing the alkalinity, leave the hot tub running for between 30 and 60 minutes and re-test.  

All this testing and retesting can be quite time consuming but it’s vital that you get the alkalinity and pH levels correct.  If they are incorrect it will potentially cause all sorts of water problems and your sanitizer is unlikely to work effectively.  Having incorrect alkalinity and pH levels can also cause foaming.

If, after adjusting the pH levels the foaming clears up, then it can be a good idea to give your filters a good clean.  This applies to any of the methods below. Once the foam has cleared then cleaning the filters will make sure that any debris, dirt or foamy residue is dealt with.

Check the calcium hardness levels – Use a test strip again to check the calcium hardness levels.  The correct level should be between 175 and 250 parts per million. If it’s less than this, then you can use a calcium hardness chemical to correct the number.  However, if there is more calcium in the water than the recommended level then the only real alternative is to drain the hot tub and start again. When you refill it, you will need to use a filter attachment on the hose and this will remove calcium from the water along with any excess metals which can be harmful to your hot tub and water chemistry.

Check and add sanitizer/shock the hot tub – After you have checked the pH levels and also the calcium hardness of the water now is a good time to give your sanitizer a boost or to shock the hot tub. Assuming that you’re using chlorine as your sanitizer give it a good boost by adding chlorine to the water until you reach a level of between 5 and 8 parts per million. Leave the hot tub for a good hour or so for the chlorine levels to reduce and during this time the water should be well sanitized.  Don’t get into the hot tub until the chlorine levels have reduced to a safe level of between 2 and 4 parts per million.

With any luck, looking after your water chemistry as above will have solved your foaming problem.  If it has, then you just need to make sure that you keep up with your water maintenance and hopefully, the foam won’t return.  If you still have a foam problem though it probably really means that you will have to completely drain your hot tub and start again with fresh water.  However, before you do this there are a few things that you can try adding to the water that might do the trick.

Add an anti foam agent

If you need a quick fix for your foam issue then adding an antifoam agent or defoamer should do the trick.  All you need to do is add a few drops to your hot tub water and the foam should disappear for up to 24 hours. Again, it’s a good idea to clean your filters after using a defoamer to get rid of as much gunk as possible.

Bear in mind that using an antifoam agent is really just addressing the symptom rather than the cause and the chances are that the foam problem will return quite quickly. If this is the case then,  if you haven’t done already, go through the steps above to check your water chemistry and sanitizer levels. If this doesn’t work, then your best bet is most likely to be to do a full drain clean and refill of your hot tub.

Add Clarifier

You might also want to have a go at adding a clarifier solution to the water. This could work particularly well if you have a cloudy water problem along with the foam. The clarifier will eliminate the foam particles and again, help the filter to capture them.  Run the hot tub with the jets on for the best part of an hour after adding the clarifier and then take the filters out and give them a good deep clean.

In a similar way to using the defoamer agent above, adding clarifier is only really a temporary fix once you have a foam and cloudy water problem. Some people add clarifier to already clean water to give it an extra sparkle, but if you are using it to solve a problem then you will eventually need to do a full drain clean and refill.

Try using Scumballs

To a certain extent, this product is worth trying if only for it’s rather good name!  A scumball or scumballs are little round sponges that you can put in the filter cartridge holder so that they float above the filter.  They help to capture bits of dirt, debris and all sorts of other gunk that can contribute to both cloudy water and also foamy water.

Clean drain and refill the hot tub.

If everything else above fails, then the only way to really get rid of your foamy water is to do a complete drain, clean and refill of your hot tub. Generally speaking, you will need to do this every 3 months or so anyway depending upon how much use the hot tub has had and how good your maintenance schedule is.  You can also test to see if it’s time to do a water change by measuring the amount of total dissolved solids or TDSs in the water. If the level is 1500 parts per million or higher than it’s  definitely time to change the water.

There’s more detail on this in my post on how to drain your hot tub here -but here’s a quick outline of how to do it.

Clean the lines –  Add a flushing fluid to the hot tub water and then run the jets for a good half hour or so so that the fluid has time to circulate around all of the components of the hot tub.  The flushing solution should loosen any bits of dirt, bacteria or algae growth from within the hot tub and leave them floating in the water ready to be drained away.

Remove the filters –  Take the filters out and either give them a deep  chemical clean or replace them if it’s time to do that.

Drain the water –  Undo the drain plug and allow the water to drain away. You can use a sump pump if you want to to speed up the process.

Clean the hot tub shell –  Use a mixture of one part white vinegar to 4 parts water or a special hot tub shell cleaner to thoroughly clean the hot tub shell. Once it’s as clean as you can get it, rinse it down thoroughly with clear water and allow the water to drain out. Do make sure that you thoroughly clean away all traces of cleaning solution as any that’s left will cause foaming problems again once you refill the hot tub.

Replace the filters –  Replace the filters with either the cleaned filters or with new filters.

Refill the hot tub –  Fill the hot tub with water from the hose.  It’s a good idea to have a filter attachment on the end of the hose pipe to remove any impurities that can cause problems with your water chemistry.

Test the water and add sanitizer–  Once the hot tub is full, test the total alkalinity and pH levels.  Test the calcium hardness and then add your sanitizer. It’s a good idea to leave the hot tub for 24 hours or so and then to test the water again before finally getting into your lovely clean hot tub for a rewarding soak.

How to prevent hot tub foam in the first place

You will now have probably realized that it’s actually quite difficult to really get rid of hot tub foam once it has taken hold.  As with many things, prevention is better than cure and, by taking a few simple steps, it’s possible to both reduce the risk of getting foam in your hot tub in the first place and also to lengthen the period of time between complete water changes.

Set a hot tub maintenance schedule –  One of the most important things you can do to prevent getting foam in your hot tub is to make sure that you are following a regular maintenance schedule. This will include regularly checking the alkalinity and pH levels of the water,  checking your calcium levels, keeping on top of your sanitizer levels and shocking your tub regularly. If you also make sure that you clean the actual hot tub itself on a regular basis these actions alone will go a long way to preventing foam build up and maximizing the amount of time between complete water changes.  You can find a helpful sample maintenance schedule for you to download and print and also lots more information about creating a hot tub maintenance schedule in my handy post here.

Shower before getting in the hot tub –  It’s a good idea to ask bathers to shower before getting into the hot tub purely from a hygiene point of view. We naturally carry around with us all sorts of dirt and grime and it can be much more pleasant for everyone if we wash as much of this off as possible before sharing a soak in the hot tub.

Apart from this, we can all easily introduce a number of chemicals and elements which can cause big problems with foamy water. So it’s a great idea for everyone to jump in the shower briefly before getting in the hot tub.  You don’t have to do a big wash and scrub but a rinse down in fresh clear water will help remove oils and soaps from the skin. It can be helpful if makeup is removed, moisturizers are washed off and hair is clean as well.

As well as cleaning ourselves before getting in the hot tub its equally as important to make sure that bathing costumes have been rinsed out in clean water as well.  Again, if you can avoid using detergent or cleaning solutions on bathing costumes this will prevent any of these chemicals getting into the hot tub water and causing problems with foam.

Avoid spilling food and drink – I know it can be great fun to both eat and drink in your hot tub and I’m by no means suggesting that you don’t do this! However, food spillages into the hot tub can cause big problems in terms of the organic matter in the food attracting bacteria. Alcohol and sugary drinks are also really bad for your hot tub water and can cause all sorts of problems with water chemistry and can lead to both cloudy water and foam problems.

Keep hair out of the hot tub – With the best will in the world, most hair will have oils, conditioners, shampoos, sprays and other chemicals in it. All of which, when transferred to the water in your hot tub, can cause big problems with foam.  Try to avoid getting your hair wet in the hot tub if at all possible. It’s not a good idea to go fully underwater in a hot tub anyway but also try to tie up any long hair so that it is at kept out of the water.  The same can be said for facial hair and beards as well. If your beard is magnificently long then again maybe tying it so that it doesn’t trail in the water would be a good idea. Otherwise, just try to keep your face out of the hot tub water as much as possible.

Don’t buy cheap chemicals –  It can be really tempting to try to save money by cutting back costs and buying cheap hot tub chemicals.  Unfortunately, this is false economy as cheaper chemicals tend to create larger build ups of total dissolved solids in the water over time.  This means that your hot tub will both cloud and foam more easily and the amount of time that you will have between having to totally drain the hot tub and refill it will be reduced.  You will also find that you need to use more quantity of a cheaper chemical to get the same effect. With cheaper chemicals being less effective all round you will probably also find that you are tempted to try other corrective treatments such as anti foam agents or clarifiers and again this just ends up costing you more money.

Remove the hot tub cover – It’s a good idea to remove your cover for a little while on a regular basis just to allow your water to breath. When the cover is off the water becomes more oxygenated and this helps to keep it fresh and clear. You can also put the jets on at the same time as this helps to introduce more volume of water to the oxygen more quickly.

Summary

No one likes having foam in their hot tub and it’s one of those things that normally is the symptom of a deeper problem. Don’t ignore it because any reasonable build up of foam indicated that your water is dirty and potentially full of bacteria.

You might be lucky and find that balancing your water chemistry and giving the hot tub a good boost of sanitizer or a shock treatment does the trick. However, the likelihood is that you will probably need to do a full water change to really fix the problem.

With a good maintenance schedule you can keep foam at bay and also prolong the amount of time between water changes. It only takes a few minutes each week and, once you have got into the habit is really easy to do. If you do this and also try to get into the habit of showering before entering the hot tub you will have gone a long way to ensuring a foam-free, long lasting and happy soaking experience!