How to Fix Murky or Cloudy Water in your Hot Tub

We’ve all been there. Heat up the tub, looking forward to getting into a beautiful clear hot tub only to find that the water is cloudy and a little uninviting. In this post I’ll share some of my experiences with how to get that water sparkling again!

Don’t empty and refill! – this is not needed in most cases.

Firstly, you don’t need to empty and refill your tub – this is not needed in most cases. It is a waste of water and also money in the chemicals that you have already put into the tub. Most likely, there is a problem with the balance of the chemicals.

Murky water just like foaming water, indicates that there is a problem with the chemical balance in your Hot Tub. Take the steps below and we will get the hot tub back to looking beautiful clean and sparkly again.

Generally, 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. Makes sense right?

Take a Chemical Test Reading

Here is the perfect Hot Tub balance.


If your Hot Tub is not at these levels, then your water is going to be murky. So, the first thing it to get your hot tub chemical balance right. We’re going to shock the tub, clean the filter and then take a look at balancing the chemicals to get to the right levels. I find that it normally takes my tub a couple of days to clear up after I take the procedure below. Again, this is drawn from my own experience and there is lots of information out there on the web. This works for me, so I wanted to share it with you all.

Step 1 – Shock the Tub

Hot tub shock is a large dose of oxidizer used to “shock” the water into a clean state after it’s been contaminated somehow. It performs three main functions.

  • It removes organic contaminents
  • It kills Bacteria
  • It removes Chloramines or Bromamines

There are specific treatments out there to do this, but I find that the easiest way is to “over dose” on Chlorine tablets. With the lid off, introduce double the amount you would put in normally for a week and run the pumps. Let the levels drop down slowly to normal levels as per the infographic above. This will make sure there are no bugs in your Tub!

Step2 – Clean the Filter Cartridge

Over time, your filter will trap all the debris too small to be caught in the skimmer basket. This will build up. If your filter is clogged up, it is not possible for it to do its job effectively. This can lead to a murky looking tub as the particles that would normally be trapped are no longer getting trapped as the filter is clogged up.

Remove the filter, user a good filter cleaner soaking overnight in a bucket. Hose down afterwards and replace. Really. easy to do. Look at my manky filter below!

You can see the dirt and debris coming off with a hose. This was before it was soaked in filter cartridge cleaner overnight, washed off again with the hose and then replaced back into the filter.

Step 3 – Balance your Chemicals

We’ve seen in the infographic above where we need to be with our chemicals. So, time to get those test strips out and add the chemicals needed to get them to the correct levels.

What Happens if pH is not right in my Hot Tub?

High pH Readings Low pH Readings
Poor Sanitizer Efficiency Poor Sanitizer Efficiency
Cloudy Water Corroded Metals/Equipment
Scale Formation Skin and Eye Irritation
Shorter Filter Runs Etched or Stained Plaster
Skin and Eye Irritations Destruction of Total Alkalinity

What Happens if TA (Total Alkalinity) is not right?

High Total Alkalinity Low Total Alkalinity
Hard to Change pH Rapid Changes In pH
Scale Formation Corroded Metals/Equipment
Cloudy Water Skin and Eye Irritation
Skin and Eye Irritation  
Poor Sanitizer Efficiency

Step 4 – Add some Clarifier

I like to add a little “sparkle” to my Hot Tub water in the form of some Clarifier solution. What this does is causes the tiny particles that come off us all when we use our tubs to combine together to form larger ones that can then be trapped in the filter. It is rather a simplistic way of looking at things and I am sure there is a more scientific explanation out there, but it does work well.

With the jets on, squirt a few bursts of clarifier into the tub and let the jets run for 10-15 mins. Over the next 24 hours, you will see a difference in the clarity of the tub.

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

Hope you have enjoyed reading and found the article useful!

Happy Hot Tubbing.

Can I Help You?

If I can help you in any way I would love to hear from you. You can get in touch using the form below.

Thanks - Andi


Hi, Andi here. I own and also write all of the articles and info pages on the site. Some years back now, I built my own hot tub but struggled to find the information I needed. So, once my tub was complete, I started this website to help others in their own pursuit of hot tub and plunge pools DIY building information.

Today, I've helped over 1000 DIY customers just like you all over the world build hot tubs and pools. Have a good look around the site, there are lots of resources here. Please do get in touch if I can help you. - Cheers, Andi

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