Quick Tip: Prevent And Clean Hot Tub [Mold, Algae, Mildew]

Most often, hot tub algae, mold, and mildew are common causes for bad smell and it can contain a lot of bacteria along the side. Although a filter can remove impurities from your hot tub, it has no effect on the bacteria in there.

If you need a quick answer to how to prevent and clean your hot tub from mold, algae, and mildew, then here it is. 

Hot tub mold, algae, and mildew are easily removed by adding more chemicals to the water such as bromine or chlorine.

The number one reason why you can see and smell mold, algae, and mildew is poor hot tub care. This includes your pH levels being out of balance.

If you have been having issues with mold, algae or mildew for a long time now, you are probably feeling tired of trying out different products. The products below should do wonders for you. You can click inside the box to order it from Amazon.


Keep in mind that it might be a good idea to drain the hot tub after shocking the water with sanitizer.

Is black mold in the hot tub dangerous?

The fungus, commonly known as the black mold, is a common issue with hot tubs that is not considered to be particularly dangerous to people. However, you should take immediate measures to eradicate it because prolonged exposure to mold can cause some allergic reactions and respiratory problems. Having black mold in your hot tub is a rather unpleasant experience, because it does not look nor smell good, and can impair your hot tub enjoyment. Besides, black mold can clog your hot tub’s filter and other equipment.

Unfortunately, hot tubs are a perfect environment for mold to flourish, and it is usually found under your hot tub cover, on the headrest, or in any area that is above the waterline. Mold forms in hot areas that are damp but not fully submerged.

The black mold formation is caused by the lack of water sanitation. If there is not enough sanitizer in the water, the black mold spores condense onto the hot tub cover and headrest, finding dark and humid areas to grow. If you notice any black mold in your hot tub, you need to change the contaminated water and clean your hot tub thoroughly to dislodge and destroy any mold that has been formed inside the pipeline.

Is it Dangerous to Clean Black Mold?

Cleaning black mold is not dangerous if you use proper protective equipment and tools. Moreover, you should not delay removing it, because it will get harder to eradicate it afterward.

When cleaning black mold from your hot tub it is necessary to provide the following: 

  • rubber gloves, 
  • safety goggles, 
  • mild cleaning concentrate, 
  • bleach, 
  • soft brush or sponge and 
  • a soft cloth. 

In addition, you should also wear a specifically designed mold mask, that will prevent the spores from inhaling. After thoroughly scrubbing the mold-affected surfaces, such as the headrest and the cover, with the soft brush and cleaning concentrate, you need to disinfect the entire hot tub. It is recommended that, before disinfection, you put on safety goggles and gloves as well as wear pants and a long-sleeved shirt to avoid getting the disinfecting solution on your skin, which may cause burns or allergic reactions.

Be advised to use a jet and pipe cleaner before the drain and refill process, or even to replace your filters, because this is the only way to dislodge and destroy any black mold that is growing inside the pipeline.

If your hot tub is extremely contaminated, you should put sanitizers in the water once more after refilling it, and then drain and clean the hot tub and refill it with pristine water again.

Are You Also Having Issues With Cloudy Water?

Hot tub mold, algae and mildew are closely related to cloudy water. Dealing with cloudy water will serve as prevention for mold algae and mildew. If you want to find out more details on how to deal with cloudy water and indirectly prevent your hot tub from getting the black and white scum, then head over to this nice article where I have it all summed up.

Black Mold

What Causes Mold, Algae, And Mildew

Even though algae, mold, and mildew are really different organic substances, they can cause equal trouble. In general, algae are categorized as plants, whereas mold and mildew are fungi, and the final decision is that you definitely don’t want them in your hot tub. However, they can be removed and we know exactly how to do it. 

AlgaeGreen – Yellow
White – Black
Hard, SanitizersWater, ShellLow pHLikes Sunlight
MoldWhite, BlackHard, SanitizerCover, Water, ShellLotions, SoapsCheck Jets/Plumbing
MildewWhite, BlackEasy, WipeCove, Water, ShellHumidity and High TemperatureMold In Early Stage

More About Hot Tub Algae

Algae can take many forms in your hot tub water and they can appear in various colors as well. They go anywhere from green to yellow to white to black. 

You may notice that your water turns greenish or cloudy, or that the sides of your hot tub shell suddenly feel slippery to the touch. 

Algae will generally form in a hot tub when the water pH levels are out of balance. Additionally, they show up when there are not enough sanitization chemicals, such as bromine or chlorine. One thing to remember is that the sunlight makes algae flourish, so make sure that you don’t leave your hot tub uncovered for extended periods of time.

Have You Heard Of Self Cleaning Hot Tubs?

I looked up some facts about self-cleaning hot tubs and decided to publish an article. I found out some interesting facts. Let’s see if you should be switching to those or not. You can read the article here.

More About Mold and Mildew

Mold and mildew usually look like a floating white slime in your hot tub water. They can also take the form of discolored white or black patches on your hot tub shell. 

Filters | White Water Mold

Mildew, on the other hand, is a surface fungus that is usually easily wiped away, while mold might be a sign of a more intensive infestation and requiring a more sophisticated approach in order to remove it. 

Mold is most likely to form in a neglected hot tub that hasn’t been taken care of properly. Usually, it is caused by soaps, lotions, or other substances that have been passed to the hot tub from your skin. Once you recognize the mold on the surface, then it would be smart to check the filters, jets, and plumbing where they also occur and grow. 

It is not rare for the mold and mildew to first appear on a hot tub cover and then spread to the water.

Is Black Mold in Hot Tub Dangerous?

Black mold, also known as Stachybotrys chartarum, is a type of mold that can produce toxins that can be harmful to humans when inhaled. Inhaling the spores or toxins produced by black mold can cause a range of symptoms including allergic reactions, respiratory problems, and in some cases, more serious health problems. If you have black mold in your hot tub, it is important to address the issue as soon as possible to reduce the risk of health problems. If you are not comfortable handling the mold yourself, it is recommended to hire a professional to remove it.

Is it Dangerous to Clean Black Mold?

Black mold can be dangerous to clean, especially if you are allergic to it or if it has grown to a large extent. When cleaning black mold, it is important to take certain precautions to protect yourself and others. Some tips for cleaning black mold safely include:

  1. Wear protective gear: Wear a face mask, gloves, and goggles to protect your eyes, mouth, and skin from coming into contact with the mold or the cleaning solution.
  2. Ventilate the area: Open windows and doors to allow fresh air to circulate and help reduce the concentration of mold spores in the air.
  3. Use a cleaning solution: Mix a solution of water and a mild detergent or a commercial mold remover, and use it to scrub the moldy surface.
  4. Dry the area thoroughly: After cleaning the mold, be sure to dry the area thoroughly to help prevent new mold growth.
  5. Dispose of materials safely: Any materials that have come into contact with the mold, such as sponges or rags, should be disposed of safely to prevent the spread of mold spores.

In general, it is best to leave the cleaning of large areas of black mold to professionals, who have the necessary training and equipment to do the job safely.

Is White Mold In Hot Tub Dangerous?

All types of mold, including white mold, pose some real health problems and should be treated seriously. You should try to remove the white mold as soon as possible in order to avoid health risks and structural damage. It is known that even milder forms of white mold can represent a health risk.

The biggest problem so far was that some people don’t realize that white mold is mold. This alone may put them at higher risk for an extended period of time. The symptoms caused by white mold include allergic reactions, eye irritations, dizziness, nausea, respiratory infections, headaches, and even mild depression.

In case you notice that you or a family member has been affected by mold exposure, make it a priority to consult a doctor and have the mold removed as soon as possible.

How Do You Get Mold Out Of A Hot Tub Cover?

There is a case where a musty smell has been coming from their hot tub and they always thought it was the water. Here is how they successfully removed it:

  1. Then they checked the chemical levels and it was always within the manufacturer limits. 
  2. They then tried draining their spa every other month but the musty smell always reappeared within two weeks. 
  3. They then discovered that the musty smell was coming from bacteria growing inside the hot tub covers. 
  4. They removed the plastic enclosed foam cover from the liners and found out a large number of bacteria that was growing within. 
  5. Using a simple mixture of 50% water and 50% Clorox they sprayed the cover and then using a small towel, they wiped the entire inside of both liners. There is an important note here: Be very careful when you remove the plastic-covered foam tops from the liners. It is a fact that Black Widows make their home there. 
  6. Make sure to inspect the liners prior to beginning any work for these insects. 
  7. In the end, the cleaning process worked and there was no more musty smell. 
  8. I left the liners hanging overnight to dry out before reinstalling them back over the plastic-covered foam tops.
CLOROX Pool&Spa All-in-One XtraBlue Chlorinating Granules, Kills Bacteria & Stops Algae, Blue, 6 Pounds
  • Dual Action Sanitizer and Shock - Clorox Pool&Spa All-in-One XtraBlue Chlorinating Granules can be used to sanitize and shock your pool water clean and clear. Cleans and clears water in one step.
  • Quick-Dissolving, Fast-Acting: These quick-dissolving, fast-acting chlorine granules not only kill bacteria but are also stabilized to protect against loss from sunlight, ensuring your sanitizer residual lasts longer in your pool water.
  • For Clean, Algae-Free Water. Kill bacteria and stop green, mustard and black pool algae with All-in-One XtraBlue Chlorinating Granules. The multi-functional XtraBlue formula kills and prevents all types of pool algae, kills bacteria, and reduces eye irritation and chlorine odor.
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How Do You Clean A Hot Tub Without Draining It?

This is a very frequent question and I feel like it hasn’t been addressed enough. Most of us would like to somehow have a quick cleaning without going through the hassle of draining the hot tub. And this is especially true if you are purchasing a used hot tub.

This is possible but with a condition that you have already maintained your hot tub properly, so now it would be easy to just monitor your pH levels and alkalinity and make sure you use enough chlorine for your hot tub. 

Now This Is How To Properly Prepare Hot Tub For Less Cleaning In The Future

In case you are not familiar with decontamination, here it is.

Decontamination is the process of Super Hot Tub Shocking to kill and oxidize everything in your tub. There are two reasons why you would want to do this. 

  • The first one is that your hot tub contains an excess amount of organic waste, and as a consequence, it is using large amounts of sanitizer. 
  • The other is that you have bacteria that are actively growing in your hot tub that has formed a protective shield (also known as Biofilm). Having normal sanitation levels will not kill it. 

You could tell about the first one quite easy by simply measuring the sanitation levels, but the latter is a more difficult case and often not recognized until after you start getting sick.

This might sound extreme to some, but I would definitely recommend decontaminating any used tub that you just purchased, especially if you have kids that plan to use the hot tub. 

You cannot be sure enough about how a used hot tub was maintained before you got it. There is no reason to take chances of becoming sick and then spending more on your medical bills than a weekend preparing your hot tub. 

So how do you do decontamination? Here’s how.

  1. You want to start by using an enzyme to clean out your pipes, such as Swirl Away, Spa Flush, etc. When you add this product, keep running the jets for 30 minutes and let sit overnight. It will clean out your pipes and deposit the gunk along the waterline. You should then wipe the waterline with a dry cloth or paper towel. Don’t forget to remove your filter before adding this product. Even better, get a new filter.
  2. Now, the next day, you must definitely drain your tub and then use some of the leftover enzymes from step one to clean the walls.
  3. Then refill the hot tub back as high as possible (above the normal waterline) with fresh water, and then install the filter you bought.
  4. At this point, you want to balance the water. TA = 80 ppm and pH = 7.2. Keep in mind that if your pH is too far out of range, it will lower the effectiveness of the Chlorine.
  5. Then add 50 ppm FC using Regular Clorox 6% Unscented Bleach. That’s approximately 1/4 gal (32 oz) per 350 gal tub.
  6. Run all jets and air features for 30 to 60 minutes. Try turning the air on and off every 10 mins, to help clean the airlines.
  7. Turn the hot tub off and drain the hot tub again. Keep in mind that this water is highly chlorinated, so you may want to keep it away from any plants and food.
  8. While the tub is being drained, use the time to clean the cover and all shell surfaces with the super chlorinated water. Rinse afterward.
  9. Finally, refill the tub with fresh water again
  10. Repeat step 4, which is to balance the water.

After these steps, you want to test your Chlorine Demand to make sure the Decontamination process worked by doing the following.

  1. Shock with Dichlor (Stabilized Chlorine) to 10 ppm FC. Important to know: Don’t use the tub. Simply let the jets run for 10 minutes, cover and let it sit 24 hours.
  2. Check FC. If FC is 5 ppm or above, you should be fine. If it is zero, then your hot tub is still using excess Chlorine, and it really needs to be decontaminated again (Absent the Spa Flush). However, this rarely happens to anyone.
Spa Essentials 32130000-02 Granules Hot Tub Chlorine, 2-Pack, white
  • Packaging may vary
  • Chlorine granules for hot tubs and spas
  • Initial dose: Add 6 teaspoons of this product for each 500 gallons of water
  • Each level teaspoon (0.17 oz.) of this product will provide approximately 1.4 ppm available chlorine in 500 gallons of water
  • Dissolves Quickly and Completely

Now when you have done it once, your hot tub should be clean like new. As said in the beginning, if you maintain your water properly, you should never have to do this again.

Have You Mastered Your Hot Tub Chemical Usage ?

It took me some time to collect everything but I was able to gather most of the questions people had about hot tub chemicals in general and published this lengthy article to be used as a guide that you now have access to.

How do I Get Rid of Black Mold in my Hot Tub?

Black mold is a common problem for hot tubs, especially during summer and winter. This is because the climatic condition offers the perfect environment for the growth and spread of these molds. 

If you use soap and other shower detergents in your hot tub, you will often experience a black mold problem. The black mold around your shower when not properly cleaned is the same black mold that appears around your hot tub when you do not observe proper sanitation.

The simplest way to get rid of this black mold is by thoroughly cleaning the tub monthly or twice a month whenever possible. Use your sanitizers regularly to get rid of mold growth-friendly environments. 

It would also help if you checked your tub’s cover often to ensure that it is not a growth base for black molds and other bacteria. Check around the zipper when cleaning to make sure that the job is done thoroughly.

How to Clean Mold from a Hot Tub?

Mold and any other unpleasant plant-bacteria will not grow in a properly maintained and sanitized hot tub. Whenever you find mold growing, check the pH levels of the tub’s water. 

You will find that this is the problem in many cases, so you will need to adjust this by adding tub chemicals to balance them out. Shock the tub after the balance to clear out the mold that had initially appeared. This will give you an effective though, sometimes, a temporary fix.

To eliminate the problem, you will need to drain the tub’s water and thoroughly clean every corner with warm water and tub detergent. Open the jets for about twenty minutes to see how they operate. If there is some resistance, close and manually clean them too. Wipe the tub clean and leave it to dry before you restart it.

How to Clean Mold from an Inflatable Hot Tub?

Like permanent tubs, inflatable hot tubs are great places for mold invasion if proper sanitation is not observed. The best way to deal with mold in an inflatable hot tub is following every sanitation process outlined in the manual. To clean the mold off, you will need water mixed with detergent and bleach, a sponge, antibacterial agents, and a dry towel.

Drain the tub’s water entirely and clean the inner and outer surfaces thoroughly. A sponge is better than a brush since the brush could have tough bristles that deal roughly with the tub’s material. Remove the filters and clean them manually as well. Use water with vinegar for this and maintain a 50/50 concentration.

Once the tub is appropriately cleaned, rinse it and wipe it dry. You can apply a safe conditioner to keep off molds for longer.

Are Algae in Hot Tub Dangerous?

Algae infested hot tub is not an ideal place to relax. The water will smell horrible, and the greenish substances you see will cause a lot of disgust. Worst of all, it is dangerous for your health to spend time in such a hot tub.

Algae is one of the bacteria that will appear in a poorly sanitized tub, meaning that you expose your skin to water that can cause a lot of irritation if not terrible skin diseases. If this water finds a way to get into your mouth and to your stomach, stomach complications will be a possible outcome. This could be accompanied by fever and diarrhea.

Unclean hot tub water is a dangerous place for people with respiratory complications such as asthma and bronchitis. This is because the steam from such water is contaminated, which can easily open up a person to triggered symptoms.

How to Clean Mold out of Hot Tub Jets?

Besides ensuring that the tub is well-cleaned and sanitized to prevent mold, you also need to pay close attention to the jets. Molds can quickly grow around this area and not get noticed until the clogging is too adverse. To thoroughly clean the mold off your jets, use vinegar, bleach, and borax. Natural detergents are also safe, such as baking soda.

If you decide to use bleach and borax, add the bleach and sprinkle some borax in the tub’s water and cover for at least an hour. The water will run through every part of the tub, including the jets, and get rid of any mold or mildew present. Drain the water and clean the tub using soap and water. Rinse and wipe the tub and let it dry before you restart it. Vinegar and baking soda come in handy when you are manually cleaning the jets during a general tub cleaning routine.

How to Get Rid of Hot Tub Bacteria?

Hot tub bacteria are harmful to the tub and even worse when your health is concerned. To get rid of this, check the quality of water you use to fill your tub. Some water sources are already infested with bacteria, bringing the same problem to your home area whenever you pump it in. 

Sanitizing will help get rid of water bacteria. Ensure that you shock clean the tub monthly and use sanitizers such as bromine and chlorine to keep it in good condition.

Drain and thoroughly clean your tub at least after every three months to keep unwanted growth from manifesting in your jets, filters, and vulnerable corners. 

Use quality detergent for this and ensure that you properly balance the pH during the refill. Keeping the pump on throughout the day is another effective way to keep off bacteria. 

Can You Clean Hot Tub With Vinegar?

Whether you want to go natural or simply save a dollar, you want to consider actively using vinegar as a cleaning tool.

When it comes to cleaning the filters, officially, filter cleaners are very acidic, probably a lot more so than vinegar. Still, a lot of people can’t see the difference when using it.

As for the smell. Vinegar washes out of just about anything very easily. People have found that vinegar works much better as a general-purpose cleaner rather than most of the bottled cleaners.

Generally, vinegar is really effective against mold and mildew. What you can do is get a mixture of 50% vinegar and 50% water. Identify the area of the cover on which the mold is growing, and then spray the mixture on it. Spray enough so that it covers the entire layer of mildew.

Can I Use Bleach To Clean My Hot Tub?

Well, you shouldn’t use bleach, but you could use dichlor. Let me elaborate.

Bleach and dichlor will both get you to the same place, just one having drastically different side effects. They are both categorized as chlorine, just manufactured in a different way.  

Bleach is sold at pool stores and usually comes in double strength to be used as liquid chlorine or liquid pool shock. This bleach is not any different than the one you buy at the local grocery store, assuming that you are buying straight, unscented bleach.

All chlorines have their pros and cons.  For example, bleach has a relatively high pH. It is difficult to transport (liquid) and loses strength over time.  These are the exact reasons why it is not recommended for use in a hot tub. Bleach is the closest to the pure chlorine, has relatively few byproducts and is almost all water.  We generally use bleach in our washing machines and commercial dishwashers amongst many other uses.

Dichlor, on the other hand, has a relatively neutral pH and is easy to transport (quick-dissolving granules). This is what makes it recommended for use in hot tubs, especially by the spa manufacturers. It is nearly 50% by cyanuric acid (aka pool stabilizer) which will build up in the spa water (especially if you shock with dichlor) and reduce the sanitizing ability of the chlorine over time.

Now if you want to explore more, there are others such as lithium, cal hypo and trichlor where all of them have the particular qualities that make them acceptable in certain uses and not so in others, but they all are the same basic chlorine.

Most people would never recommend bleach as a primary sanitizer. They would only suggest it in order to get the ppm level up that high and that quickly. It is the cheapest and easiest solution out there.

Picture of Emily Williams

Emily Williams

Emily is a passionate Hot Tubs researcher who loves writing about all things Hot Tubs! She has years of experience and a knack for simplifying complex concepts, these articles are here to answer all your burning questions in a simple and easy to read style.
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