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Getting Rid Of Mould In An Inflatable Hot Tub – Quick Guide

If you have an inflatable hot tub, you know how important it is to keep it clean. Knowing how to clean mould off a hot tub properly will keep your hot tub hygienic and safe.

A dirty hot tub is a haven for bacteria which could result in health issues and the unit not performing at its best.

However, if you have not used the spa for a while, have added the incorrect dosage of chemicals or stored it away for the winter, you might notice some signs of mould.

In the ten years, we’ve been running this site, what is the best way of getting rid of mould in an inflatable hot tub, is a question we have been asked numerous times.

This is the post where we go deep on hot tub mould removal.

Mould doesn’t look or smell great and can cause health issues, so it’s essential to remove it.

This blog post will discuss how to get mould stains off an inflatable hot tub and provide step-by-step instructions on how to get the job done quickly and efficiently.

Establish Whether it’s Mould Stains, Mildew or Slime

All three are similar and are caused by not performing regular maintenance or neglect. But the good news is by following these steps, whichever one is causing a problem, it will soon be gone for good!


mould growing on a surface

Mould is a fungus and if present, you will notice either white or black patches on the hot tub shell, in the jets or floating white slime in the water. It can be caused by lotions and other substances bathers may have on their skin. 

Here’s a guide about how to get rid of slime in a hot tub.

Once established in the pump or jets of a neglected hot tub, it continues to grow and can have severe implications for your health. Mould can cause allergic reactions, breathing difficulties, skin irritation, and even mild depression,  so removing the harmful bacteria immediately is crucial!


This fungus loves warmth and moisture, so a hot tub is the perfect breeding ground. It takes the form of black specks on the surface of your spa and is easily wiped off with a damp cloth, unlike mould, which is the result of a more intensive infestation.


Hot tub algae growth is usually caused by dirty water, leaving your hot tub uncovered or an imbalance in the PH level. Algae is slightly different to the other two as it is a plant, not a fungus. 

Algae can be a range of different colours and will discolour the water and make the hot tub surface feel slimy. Sunlight makes algae flourish, so it may become an issue if you’ve left the hot tub uncovered for a few days.

All three are easily addressed by keeping your inflatable hot tub clean, although we’ll concentrate on mould in these seven steps.

If you see yellow marks, then this page explains how to get yellow stains out of a hot tub.

How to Get Rid of Mould Inside an Inflatable Hot Tub

1. Remove Debris

Before you begin to clean your inflatable hot tub, you should remove any large debris, plants or other green stuff as it may jam the drainage valve when you empty the tub. You can scope out leaves etc., with your hands or a spa net or even invest in a hot tub vacuum, which will definitely make your life easier.

2. Shock Your Inflatable Hot Tub

Shocking your inflatable hot tub is the best way to remove mould from an inflatable hot tub. It oxidises the spa destroying the electrons on nasty molecules so sanitisers can effectively eliminate them.

Below we explain the process briefly. Here is a guide covering how to shock you Lay Z Spa if you have this brand.

First, you need to determine if your PH levels are correct. Shock treatments work best between a level of 7.2 and 7.6. In fact, performing a shock treatment with a PH level of 7.5 will be twice as effective compared to if the PH level is 8.00.

There are a few crucial things to remember when shocking your inflatable hot tub.

Different treatments have varying strengths, so reading the label before adding hot tub chemicals is essential. This page lists the top hot tub starter kit to buy. (Never use pool shock, it’s easy to overdose, the formula may contain chemicals which are not required for spas and the larger bags may be a safety hazard if not used in one use.)

chemicals being poured into a jacuzzi

It is vital not to overdose or underdose your shock treatment and it’s very easy to do both. Not administering the correct dose to hot tubs will either see the treatment being completely ineffective or, if you add too much, the resulting gases may cause skin irritation or breathing issues.

It’s essential to take precautions when using any chemicals, especially with chlorine. Add carefully, keep away from pets and children and store safely.

Once you have added the shock treatment, leave it to do its thing for around 20 minutes (No Jets). You are then ready for the next step

3. Drain The Tub

After shocking the Jacuzzi, you are going to need to empty it into a safe area. Remember, the chemicals will be hazardous to vegetation and aquatic life, so you need to be careful where your hot tub water is drained.

Most inflatable hot tubs have a valve for draining, which makes the process much easier. However, you may have to look for an adapter for your garden hose online. Once you have read the owner’s manual for directions, you can simply attach your hose and direct the water away from your flower beds.

Want to know how often to change hot tub water? Check this out

4. Clean Or Replace The Filters

someones cleaning hot tub filter with a hose

Once you have drained your spa, it’s time to examine the hot tub filters. Filters collect all the organic matter and dirt that gets into your hot tub, so they are generally full of bacteria, meaning they need to be cleaned and replaced regularly.

You can use a mild detergent and your garden hose to clean them thoroughly; if they don’t look like new, are stiff or discoloured, they need replacing.

You should clean the hot tub filters after every use and replace them every few weeks, depending on how often your inflatable hot tub is used. It’s here for the best spa filters to buy.

5. Wipe The Inflatable Hot Tub Surfaces

Now is the time to clean both the interior and exterior sides of your hot tub. It’s important not to use a stiff-bristled brush as this can damage the material. A sponge, soft cloth or microfibre cloth are much better options for cleaning mouldy sides.

someone picking out debris of a hot tub with a net

There are a few hot tub cleaners to help with mould removal and keep your hot tub clean; you can go for a commercial cleaner like the Pro-Kleen Antibacterial Hot Tub & Spa Surface Cleaner Spray, use a mild detergent such as Fairy Liquid or use diluted bleach to remove stubborn mould.

There are also natural products for those worried about the planet. 

One way to clean is with Vinegar as it’s an excellent mould remover and its acidity level of around 2.5 means it’s strong enough to tackle tough stains without the risks associated with using harsh chemical products. Simply combine equal parts water and vinegar in a spray bottle and leave it to work on the mould for around 20 minutes or at least an hour for stubborn stains.

(One thing to be aware of is not to never mix vinegar with bleach when cleaning your inflatable hot tub, this produces Chlorine gas which can be extremely dangerous if inhaled) 

Baking soda is often touted as one of the best natural cleaners and it can be effective if your inflatable hot tub is covered in mould. Because it boasts a neutral PH level, it is safe to use even if pets and children are around and it also has deodourising properties, so it gets rid of that nasty mould smell.

container with liquid being poured

Bleach is one of the Jacuzzi cleaning products we all have. Bleach has the added benefit of killing bacteria as well as removing mould, but it should be used on a hot tub with caution like chemical cleaners. If you decide to clean your hot tub with bleach, dilute it down with an equal amount of water to form a correct mixture.

Make sure to get into all the nooks and crannies; bacteria loves to hide in the hard-to-reach places of hot tubs and the job will all be for nought if you leave any behind.

You might need a bit of elbow grease, but once the surfaces of your hot tub are thoroughly cleaned, you can give them a thorough rinse to remove any residue. If you are storing your hot tub for the winter, ensure that everything is completely dry before packing away,

6. Clean Liners, Covers and Accessories

There’s no point spending hours getting your hot tub gleaming to then forgetting to clean the hot tub cover, jet nozzles, filter pump, placing a dirty cover on top or adding greasy accessories.

Inflatable hot tub covers are a giant breeding ground for mould and mildew, so it’s vital to keep them spotless. You can use the same solution as you did for the hot tub; just ensure that if you have an inflatable hot tub cover, you clean the bits hidden by the inflatable part.

And, whilst you have everything to hand, it’s a good idea to wipe any accessories such as headrests, seats or floating drinks holders with a gentle cleanser as these can harbour bacteria and surface fungus. 

Now you have done the hard part; it’s a simple matter of refilling the tub, adding the chemicals and getting it back up to temperature. You can now have people around your home and enjoy a clean tub again.

Tips to Keep a Hot Tub Mould Free

Below find some quick-fire tips and tricks you can use for cleaning inflatable hot tubs. If you are new to owning a hot tub, then visit this page for guidance on how to maintain a hot tub where we show you general practices you should know.

someone in a body suit checking mould on a wall

Keep the PH levels regulated.

As we’ve touched on above, the right PH level is essential to keeping your hot tub water clean and crystal clear. Bromine and Chlorine will only work effectively between the range of 7.2-7.6, so invest in some testing strips and check levels before use.

Use Bromine

This is what kills any bacteria in the water. You want to keep Bromine levels at 1-3 PPM (parts per million). Start by adding 1-2 tablets and remember to wait 12 hours before using the spa. Test levels regularly in case you need to add more.

Use a shock treatment regularly.

Using these treatments allows the sanitisers you use to work at their best, so it’s essential to shock your tub on a regular basis. If you notice a smell coming from your tub, it means the Bromine is killing the bacteria, so a lot of smell equals a lot of bacteria. Using a shock treatment will reduce the smell, get rid of bacteria and prevent mould from developing.

Have a shower before entering the spa

someones hand under a running shower

Lotions, hair and beauty products, make-up and fake tan produce a lot of residue and bacteria in the tub, leading to mould. It’s crucial to shower before using a hot tub to prevent the build-up of dirt and organic matter in the water.

Drain and thoroughly clean your tub every six weeks

If you enjoy a soak 2-3 times a week, it’s good to drain and completely clean your tub every six to eight weeks. Over time, the molecules, oils and organic substances build up and you don’t want to wait until mould appears before addressing the issue as it can cause health problems if left too long.

Use absorbent sponges

These handy little accessories can be bought cheaply online and are just popped into the spa. They absorb oils, teeny insects and any residue in the water, helping to keep the water clean, crystal clear and reducing maintenance requirements.


How to clean mould from inside a Lazy Spa

Is black mould in a hot tub dangerous?

Cleaning black mould from an inflatable hot tub is something you should do. Mould, in small doses, is not directly harmful; however, it looks unsightly and may give off an unpleasant smell that no one wants when enjoying a leisurely soak.


Although mould is a common issue that all inflatable hot tub owners face at some point, it doesn’t mean you have to put up with it. With a thorough cleaning process, keeping your tub covered and maintaining pH levels, you can make sure that any mould build-up is eliminated quickly and easily.

White vinegar, bleach mixed with warm water, or commercial cleaners can be used to remove mould from your hot tub. However, be sure to use a soft cloth or magic eraser rather than a scrubbing brush to not damage the shell and wash the outer cover too. 

If you need more advice on how to remove mould from an inflatable hot tub and keep your spa water pristine, be sure to read our other cleaning articles for helpful tips and tricks. Thanks for reading!

John Devlin

Hello, Welcome to my website. I’m John, and I created the InflatableHotTubGuide while researching these spas nearly a decade ago. Since its creation, the site has become the leading UK resource for many models. As a passionate hot tub user, I love to test and explore all the latest machines this industry keeps creating. I hope you find our content helpful.