What Is the Black Stuff Coming Out Of My Jacuzzi Jets?

Heather Robbins
by Heather Robbins

A Jacuzzi is a great way to add a sense of calm and luxury to your home. However, there is nothing luxurious about getting into a Jacuzzi full of chunks of black flakes. So, what is the black stuff coming out of my Jacuzzi jets?

The black stuff that comes out of Jacuzzi jets is biofilm which consists of bacteria and grime. Dirt, grime, dust, black mold, and even viruses can clump together and form a biofilm. A biofilm is a collection of living organisms that form a black slime, and you can eliminate one with white vinegar or a bio-cleaner.

It isn’t the end of the world if black stuff comes out of your Jacuzzi jets, but you need to address it. The presence of bacteria in a hot tub can be dangerous, off-putting, and uncomfortable. Follow along as we address what it means when black stuff comes out of your Jacuzzi jets.

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What Is the Black Stuff Coming Out Of My Jacuzzi Jets?

The black stuff that comes out of Jacuzzi jets is typically a biofilm made of many microorganisms. It is easy for dirt, bacteria, parasites, and mold to accumulate in a Jacuzzi. Over time, the combination of dirt, viruses, and impurities bind together and thicken into a black mass.

A biofilm is typically black because it creates a slime to protect itself so that it can continue to grow. The black biofilm can come out of your Jacuzzi jets and circulate throughout the tub. Sometimes, the black stuff in your Jacuzzi isn’t a biofilm and is instead simple dirt and grime.

Dirt and grime are much easier to remove from a Jacuzzi because it isn’t necessarily alive like a biofilm. Certain soaps and shampoos can also show up as thick, black grime that comes out of your Jacuzzi jets. However, the cause is typically a living biofilm that you must treat and kill to remove it from your Jacuzzi.

How to Clean Jacuzzi Jets

You can eliminate dirt, grime, black mold, and biofilm in your jacuzzi if you clean it properly. The best bet is to clean your tub and the jets to ensure that you remove all of the impurities that seep from the jets. Let’s take a look at how you can clean your Jacuzzi jets when there is black stuff coming out of them.

1. Fill the Tub

Fill the Jacuzzi tub with hot water up to 1”-2” past the highest jets. You need to fill the tub higher than the jets to ensure that the water can pass through each one to clean them. Make sure to use as hot of water as possible to kill as much bacteria and grime as you can.

2. Add Vinegar

White vinegar is a household item that can clean just about anything, and that includes Jacuzzi jets. Pour ½ gallon of white vinegar into the water and turn the jets on for 10-20 minutes to circulate the vinegar. The acidity in the vinegar can kill germs, viruses, and bacteria that contribute to the black biofilm.

You can substitute the white vinegar with a bio-cleaner such as Spa System Flush or Bio-Kleen. Bio-cleaners are effective because they are meant for hot tubs and can effectively clean the entire tub. Follow the directions for the specific bio-cleaner that you choose so that you don’t use too much which can cause damage.

3. Drain the Jacuzzi

Turn off the jets and drain the Jacuzzi after you let the bio-cleaner or white vinegar circulate for 10-20 minutes. Only drain 2” of water from the Jacuzzi and look for the scum that remains where the water once was. Remove the scum that remains with a brush or clean cloth.

Now, add more white vinegar or bio-cleaner and fill the Jacuzzi with 2” of hot water.

4. Run the Jets

Run the jets again for another 10-20 minutes. The white vinegar or bio-cleaner should eliminate the scum that remains. Drain another 2” of water from the Jacuzzi and wipe away any grime that you find in the tub.

You may need to use a stronger bio-cleaner if black stuff still comes out of your Jacuzzi jets. Otherwise, you can simply repeat the process another 2-3 times until nothing comes out of the jets. It may take a while depending on how much biofilm you have in your Jacuzzi jets.

How Often Should You Clean Your Jacuzzi?

The best way to ensure you never have to deal with this issue is to prevent the build-up of biofilm and other debris via regular cleaning. How often do you need to clean your tub?

Before And After Each Use

Cleaning as soon as possible after you’ve used your tub is much easier than if you leave the debris to dry and harden. However, if you haven’t been in it for a while, it makes sense to do an additional clean before you get back in.

A Deeper Clean Monthly

Even if you haven’t used your tub regularly, a scheduled monthly clean is good practice and will prevent those black flakes from spoiling your next soak session.

Or, if you rarely use your tub, it’s suggested that you deep clean before each use, that way you won’t get any dust, or other particles swimming in your bath with you.

DIY Jacuzzi Whirlpool Bath Filter

There’s a simple technique you can use for Jacuzzi tubs to make sure that your jets stay clean, and it costs next to nothing. All you need is:

  • A coffee filter
  • A rubber band

Place the filter over the return pump drain and use the rubber band to hold it securely in place. The filter will capture any biofilm or debris that comes out when you circulate the cleaner. To work effectively, you should run only hot water through the jets for just over 30 minutes.

With regular use, the coffee filter will need to be changed at least every two weeks. If you prefer to purchase a normal filter from the supplier, this only needs to be replaced every twelve months to keep your system free of build-up.

How To Maintain a Jacuzzi

The amount of maintenance depends on how often you use the tub. If you use it regularly, then cleaning after each use and a monthly deep-clean will be required. On the other hand, if you only use it occasionally, you may choose to deep clean every 3-4 months.

Now, if your jets are ever clogged, you will need to clean them out. The reason is that eventually whatever is clogging it up will cycle through the water while the jets are in use. It’s better to find out what that is while you’re cleaning your jets.

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Related Questions

Are jetted tubs unsanitary?

With proper cleaning and maintenance, whirlpool systems are safe. When they were first introduced, flexible piping was often used.With time, due to the weight of the water they carried, this would start to sag so that water wouldn’t drain properly.However, modern systems eliminate this problem either using rigid pipes that won’t sag and allow water to pool.

Can you run bleach through a Jacuzzi tub?

Although you can use bleach, it’s not recommended as it can damage the unit’s components over time. Check the manufacturer’s guidelines.

Can you use dishwashing tablets to clean a jacuzzi?

Some sites recommend these, as they contain a low-foaming detergent. However, they will create a protective coating on the biofilm and debris you’re trying to remove. Therefore it’s better to avoid them.


Whether you choose a specific spa and whirlpool product, a bio-cleaner or a homemade solution such as white vinegar, the most important thing you can do is clean your tub after each use and carry out regular maintenance. This will ensure that your tub remains hygienic and free from debris so that you can get full use and enjoyment from it.

Heather Robbins
Heather Robbins

Heather is a passionate writer who loves anything DIY. Growing up, she learned everything from home repairs to design, and wants to share her tips with you. When she's not writing, she's usually hiking or searching for her next DIY project.

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