Hot Tube, Uncategorized

How to deal with cloudy hot tub water

Cloudy water in your hot tub is probably one of the most common issues that hot tub owners suffer with. Hot tub water can quickly lose its clarity. Your water can quickly turn from being crystal clear to a hazy and dull very quickly.

What is this cloudiness in my hot tub water?

The milky looking water is caused by suspended particles in the water giving the water it’s cloudy look. These particles are too small to touch and too small to get picked up in the filter, so they just pass straight through, staying in the water. These particles can be a variety of different substances:-

  • Insoluble matter
  • Organic debris
  • Cosmetics like lotions and moisturisers
  • Dead algae

In the majority of cases, the particles are introduced by the bather. If you consider that unlike a swimming pool a hot tub contains a very small quantity of water for each person. Ultimately there is a larger concentration of particles in the water which causes the cloudiness.

Why do I get cloudy hot tub water?

These particles that are suspended in the water could be different materials

Environmental debris – Insoluble matter such as dust and dirt from the outside

Organic matter – this would come from the bather and can consist of different organic matter such as skin cells and body oils.

Other organic materials could be algae, but rare in a hot tub.

Man-made contamination – Again most likely introduced to the water from the bather, these could include cosmetics such as detergents, make-up, lotions and moisturisers. They have washed off the bather into the water.

Heavy usage and low sanitizer level.

Why doesn’t my hot tub filter clear the water?

It makes sense to think that all hot tubs will have some form of filtering system, so why don’t they remove these particles? Well, the main reason is that the particles are just too small for the filter to collect them. They just pass straight through the filter material and back out into the water again. Most filters will remove particles down about 5 -10 microns in diameter, which is still pretty small but to give you some idea a red blood cell is about 5 microns in diameter.

In addition, most hot tubs are designed with some form of by-pass plumbing to the filter which means that in some cases that not 100% of the water will pass through the filter. One reason for this system is that if the filter is blocked water can still circulate freely and not cause damage to any components.

How do I make my water clear again?

Empty and refill your hot tub

Have you tested your water chemistry? Firstly make sure your core levels are correct:-

  • Ph: 7.4 – 7.6
  • Total alkalinity: 100 – 150 ppm
  • Sanitizer: – Chlorine 3 – 5 ppm / Bromine 4 – 6 ppm

Having low sanitizer levels can cause cloudy water as there just isn’t enough ‘fuel in the tank’ to cope with the organic matter being introduced into the water.

Shock treatment

Probably the best way to treat cloudy water is by what’s commonly known as ‘shocking’ your water. Shocking your water will oxidise any organic matter. This means it will burn off the organic matter which is usually the most common form of contamination in hot tub water and turn it into a gas, therefore, removing it from the water. There are a variety of chemicals which will do this

  • Non-chlorine shock (preferred) – add 20g per 1000 litres of water (average hot tub is about 1500 litres) Remove hot tub cover and allow to circulate for up to an hour for full effect.
  • Chlorine granules – Increase your free chlorine level to 20 ppm and allow to circulate with the cover off.
  • Bromine granules – Increase your bromine level to 20 ppm and allow to circulate with the cover off.

The preferred treatment is a Non-chlorine shock as you will be able to use the hot tub after treating. By using chlorine or bromine granules, you will need to wait until the level naturally reduces to an acceptable level before using the hot tub again.


The filter in a hot tub is often overlooked. Your hot tub filter requires regular cleaning, a blocked filters mean that they aren’t doing their job properly, so make sure filters are rinsed regularly and treating with a filter cleaner periodically to remove oils and greases. New filters need fitting every 6 – 12 months.


clarifier is a speciality water treatment. It works by coagulating the small particles in the water which are causing the cloudy water into larger particles. These particles are then large enough to get caught in the hot tub filter and therefore removes them from the water. When you use this treatment, make sure you rinse out your filters to remove the extra debris that has been taken out of your water.

How can I prevent getting cloudy water in my hot tub?

The best cure by far is prevention. By not introducing the contamination to the water then you will remove the possibility that you will get cloudy water, we suggest the following steps to reduce cloudy water

  • Shower before using hot tub (don’t use any soap, just rinse off in the water)
  • Don’t wash swimming customers in detergent. Just rinse them in warm water after use
  • Clean filters regularly
  • Make sure your water chemistry is correct
Outdoor Shower


Cloudy hot tub water is probably the most common issue experienced by hot tub owners. Caused by particles that cannot be removed by the filter alone. If you suffer from cloudy water we suggest the following steps:-

  • Drain and refill if you water is over 8 weeks old
  • Make sure your water chemistry is correct, especially sanitizer levels
  • Use a non-chlorine shock treatment or water clarifier
  • Clean out your filters

Hopefully, you have found this article informative and useful, and the suggestions have helped sort out your cloudy water problems. If you have any questions or comments about this article please feel free to contact us.

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