How to get rid of hot tub biofilm

how to get rid of hot tub biofilm

What is hot tub biofilm?

Hot tubs without chemicals or maintenance.

That’s the dream. 

Sadly there is still no way to fully achieve this. But helping to prevent and remove biofilm can help reduce the level of maintenance required. And lower the levels of Chlorine and Bromine you need to use on your hot tub.

But what is hot tub biofilm?

Biofilm is essentially hot tub plaque. It’s a protective layer of slime that forms and houses bacteria and calcium. It forms in the hard to reach areas such as pipes, pumps and heaters. And it is virtually impenetrable by Chlorine or Bromine. 

If biofilm builds up it can prevent the sanitisers from working effectively to kill bacteria. In some cases, sanitisers alone are as little as 1% effective in killing bacteria.

The formation of it not only leaves the hot tubs open to harbouring bacteria, but it can lead to a number of water problems, such as: cloudy water; foaming water or an unpleasant odour. 

Your natural instinct in this case is probably to throw some more sanitiser in to kill the bacteria. But this only leads to costly use of chemicals, and will not deal with the root problem.

So how do we get rid of biofilm?


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How to get rid of hot tub biofilm

DryOxIf you have been running a hot tub for a while. Or, if you are starting a hot tub back up again after a while, you will likely already have biofilm formation.

Tell tale signs are flaky white particles in the water. Or you may be going through more sanitiser than you used to. 

In this case you need to eliminate existing biofilm and bacteria.

To get rid of it we recommend using a biofilm eliminator such as DryOx. Which, forms a gas that can penetrate the biofilm, destroying it and any lingering bacteria.

To use this:

1. Fill up your hot tub (if it isn’t already full)

2. Heat the water. DryOx works best at 20 degrees and above

3. Add the tablet

4. Let the pumps run for 1 hour, so it circulates through the pipework

5. Leave in the hot tub overnight (for 12 hours)

6. Drain the hot tub down before cleaning and refilling as normal.

(Please follow the instructions on the packet for safe use)

We also recommend using DryOx as part of your quarterly servicing programme before your drain down your hot tub.

How to prevent hot tub biofilm

If you’ve got a brand new hot tub. Or if you’ve just managed to eliminate the biofilm using the above solutions we recommend keeping on top of it and preventing further biofilm formation.

For this we recommend using O-Care. A safe, soft and simple weekly solution for preventing hot tub biofilm. You add it using the included measuring cups as part of your weekly checks. 

  • Helps reduce the amount of sanitiser by up to 78%
  • Odourless and will leave your skin feeling soft
  • Easy to use, lasting 3-5 months

Do I still have to use other hot tub chemicals?

Will treating biofilm eliminate the need for other chemicals?


You will still have to check the pH and add sanitiser.

The good news is that by eliminating and preventing biofilm you allow the sanitisers to work more effectively. And reduce the levels of sanitiser you need to add to the hot tub. So you can use less chemicals with better results. 

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In summary

Biofilm is often the forgotten hot tub problem. People obsess over Chlorine and Bromine levels but don’t give too much though to why they are having to use so much.

Preventing and eliminating biofilm is important to ensure that your hot tub isn’t harbouring any unwanted bacteria. And to help you lower the levels of chemicals in your hot tub. Making it safer and more environmentally friendly. 

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Debbie Ekins
Debbie Ekins
Eagle Leisure - Sales & Marketing Manager Mission = to arm you with the knowledge you need to make the best buying decisions. Fuelled by coffee (and naps). Explorer of Scotland and the world.