White Flakes in Your Hot Tub: Removal and Prevention Tips

Michael Keenan


Hot Tub Troubleshooting

There’s nothing worse than finding white flakes floating around you in the hot tub to put a damper on your relaxing spa night. It’s just gross! Not to worry, it’s easily sorted – I’ll teach you how to remove white flakes from your hot tub and how to prevent them in the future.

I’ll explain a few things along the way. What these flakes are, what causes them, and how to prevent them. Let’s have a look ….

white flakes in hot tub spa

Quick Answer:

White flakes in a hot tub are caused by calcium scale deposits or biofilm growth (white water mold). Test to identify the flakes then treat accordingly.

  • Calcium scale deposits are caused by high calcium levels in your water. Clean and balance the water to remove.
  • Biofilm growth usually happens when your spa hasn’t been used for a while. Clean with a good sanitizer.
  • Regular water testing and a regular maintenance schedule will prevent white flakes.

What Are These White Flakes in Your Spa?

White flakes filming over your hot tub or floating around near the drains is not a pretty sight. If your hot tub water is looking flaky and gross there are two possible culprits.

  • Biofilm growth (white water mold)
  • Calcium scale deposit

It’s normally one or both of these things causing your problem. I have heard of times when people have seen dead skin floating in the spa – which is just so gross! Hopefully, you never let things get that bad.

Biofilm Growth – White Water Mold

Biofilm growth is also known as white water mold. Biofilm growth usually happens when the hot tub hasn’t been in use for a long time. This thin film of mold develops when you neglect to clean your tub and leave the water stagnant.

The water in your hot tub is usually set between 102 to 104 degrees Fahrenheit. This temperature setting in your hot tub also makes it an extremely vulnerable place for mold and bacterial growth.

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Calcium Scale Deposits

Your water can develop white flakes if it has high calcium content. Some amount of calcium should be present in your hot tub water to keep the tiles and the equipment from wearing out too soon.

If the calcium hardness in your hot tub water is low, you might feel slimy and unclean when you get out of the tub. Too much calcium, however, will solidify and form flaky deposits in the water as well as on your heating equipment.

Ideally, the calcium hardness in your hot tub water should be between 100 to 150 parts per million. Find out more about hot tub water chemistry in my main guide here.

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Test Your Flakes First

You have to follow different procedures to get rid of calcium deposits and biofilm growth. So the first thing you have to do when you notice these white flakes in your hot tub water is to get them checked.

This is a fairly simple process that you can do yourself. You don’t need any professional help.

  • Collect some hot tub water and flakes in a clean glass or bowl.
  • Add 15-20 drops of bleach or liquid chlorine to the water you collected.
  • Stir the solution and let it sit for 30 minutes.

If the flakes disappear after 30 minutes, you have biofilm buildup in your hot tub.
If the flakes are still there in the cup after 30 minutes you have calcium flakes in your hot tub. Don’t you love a simple testing solution?

What Does Calcium Buildup Look Like in Hot Tub?

In the image below you can get an idea of how white flakes caused by calcium buildup or white water mold look in your hot tub look. This isn’t a particularly bad build-up – it can be much worse. Still, you wouldn’t want to relax in there!

calcium flakes in a spa

How to Get Rid of White Flakes in a Hot Tub and Prevent Their Return

Now that you’ve identified what is causing the white flakes, it’s time to find a solution and keep the flakes away for good. While a thorough cleaning can get rid of biofilm deposits, calcium deposits require a regular balancing of hardness causing minerals.

Below I’ll explain how to remove white flakes caused by biofilm growth and by calcium deposits and tips to prevent this in the future:

Biofilm Growth

This usually occurs because you don’t sanitize your hot tub regularly. Using a sanitizer that works well and is easy to manage is important. If you are not happy with the quality of your spa water have a look at using alternative sanitizers – I list a few good ones here.

It can also occur if the water has remained stagnant for a long time due to the irregular use of the hot tub.

Once you have identified that your white flakes are a result of biofilm, it is fairly easy to solve. A good cleaning out and regular maintenance will keep these flakes out of your hot tub.

How to Remove Biofilm Growth

You must drain the hot tub and use a biofilm cleaner – these are not regular hot tub sanitizers, they are specifically designed to tackle biofilm buildup. Follow my guide on how to drain and clean your hot tub.

Make sure that you clean your filters using the product. Replace the filter if you feel they are damaged beyond repair.

After you clean the hot tub using the biofilm cleaner, fill it back up, balance the pH, and add chemical disinfectants like chlorine or bromine. For more details, I have a guide on how to get rid of white water mold here.

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How to Prevent Biofilm Growth:

Use Your Hot Tub Regularly

Don’t leave your hot tub unused for long periods of time. Biofilm develops when the water remains stagnant for too long.

Follow a Cleaning Schedule

Follow a regular sanitizing and cleaning schedule for your spa. The warm temperature in the hot tub makes it an ideal breeding ground for mold, green algae, and bacteria.

If you’re on a regular cleaning routine you don’t have to worry about flaky water or skin infections as a result of the bacterial growth in your hot tub.

Calcium Build Up in Hot Tub

Calcium buildup or deposits form in your hot tub because the chemical balance in your hot tub water is off. If you live in an area with hard water, you will face calcium deposit problems if you don’t test your hot tub water frequently.

How to Get Rid of Calcium Flakes in a Hot Tub

  • Drain the tub, wipe it down, and let it air dry.
  • Spray a mixture of vinegar and distilled water all over the dry tub. This will soften any calcium deposits in the tub.
  • Scrub out the tub with a brush. Use some more mixture for stubborn buildup.
  • Rinse and wipe the tub down.
  • Refill the hot tub and check the chemical levels.

How to Prevent Calcium Deposits

Balance Your Water

Balance the alkalinity and pH levels in your hot tub water. If your pH is too high that means your water is hard and has high levels of calcium. The calcium will eventually solidify and break down into flakes.

Regularly test your hot tub water either using test strips or a liquid testing kit. You can even get your water checked out professionally at your local hot tub dealer’s office.

Try Using Scale Preventer

Scale preventers are similar to water softeners. They are additives that help in reducing the hardness of your water.

You can get scale preventers from hot tub manufacturers or suppliers. If your area has very hard water you can treat your hot tub water every week with these scale preventers to avoid buildup.

They are a really good idea as they help prevent both calcium scale and biofilm. Both can lead to a white film on the hot tub walls and if left untreated for long enough you can end up with brown flakes in your hot tub!

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In Conclusion

Having white flakes in your hot tub is a very common problem. The good news is that this is one of the easy problems to fix and prevent. Follow my guide and keep a good maintenance program.

You don’t want white flakes in your hot tub and you certainly don’t want to give anyone skin infections just because you forgot to clean your hot tub.

If you forget to disinfect your spa regularly, not only will you lose face in front of other people but you might also end up having to spend a lot of time and money to clean it up later on. Prevention is always better than cure!

michael keenan author

Author - Michael Keenan

I'm Michael Keenan the owner and creator of the Outdoor Care Guide. I'm a trained horticulturist with over 30 years of experience in pool care, plant care, and landscape care! Seemed like a good idea to share - I think I can make your life easier and save you some time and money!