In this guide, we’ll show you how to clean biofilm from hot tub. If you didn’t know, the sheer amount of chemicals in your hot tub’s water may put most people off.
However, it’s a necessary evil in the sense that you can’t possibly think about replacing the water on a regular basis, and the only solution is to keep the water free from bacteria by adding sanitizers such as bromine and chlorine.
However, these are not the only two chemicals that are added to hot tub water. In fact, a bunch of pH decreasers or increasers have to be added to balance the total alkalinity and the pH value of the water.
Do you usually have to add more chemicals than necessary into your hot tub? Does the water often develop a layer of foam? If that is the case, your hot tub might be susceptible to a biofilm problem.
In the following article, we will talk about the effects of biofilm on your spa, what it does, and more importantly, how you can deal with the problem. But, before we get started, it’s important to understand what biofilm really is.
What Is Biofilm?
The simple definition of biofilm is essentially a group of microorganisms or bacteria that like to glue themselves on surfaces that are generally exposed to water on a constant basis.
It’s generally a pretty common issue that arises in hot tubs and other pool surfaces, primarily due to problems with the quality of water and the excessive use of chemicals.
Biofilm usually starts to increase in the main hot tub pipes as well. It likes to stick to multiple exposed surfaces and creates an additional layer. You may have seen this on hot tubs and the walls of your local swimming pool.
When the water recedes, the surface feels a bit slimy. This biofilm is capable of resisting the common sanitizers used for treating the water for bacteria, such as bromine or chlorine.
It’s the internal pipes and the filtration system installed in your hot tub that provides an excellent platform for biofilm to grow rapidly.
Even though biofilm can develop over time naturally in different kinds of circumstances, this bacterial film does really well in darker and warmer environments, where moisture levels are incredibly high.
When you factor in the organic material that is added into the water from humans interacting with it on a daily basis, especially the soaps, the lotions, the deodorants, and of course, the excessive sweat that is released into the water, it’s easy to understand why bacterial film tends to grow so easily in the internal pipes.
Since the tubs provide such a range of conditions for bacterial film, even the newest hot tubs, especially ones that haven’t even aged a year or so, usually succumb to this problem.
What Can Biofilm Do to Your Hot Tub?
Biofilm can have a range of effects on your hot tub. When you add any kind of sanitizer into the water, be it chlorine or bromine, it immediately gets to work in destroying the bacterial presence.
As soon as the molecules of the sanitizer find any bacteria, they kill it. As it kills more and more bacteria, the sanitizer molecules also begin to change, eventually becoming unable to kill the bacteria, and they get filtered.
Biofilm, on the other hand, acts like a sponge. It is capable of absorbing the water sanitizers that you add.
If there is an excessive amount of biofilm buildup in your spa, you should know that the addition of bromine or chlorine is not going to be as effective as you might think.
A large quantity will simply become ineffective as it continues to fight the biofilm, which, as mentioned above, is capable of resisting it.
As a result, you lose sanitizer, but the biofilm doesn’t sustain any damage whatsoever. Once all of the sanitizer in your water has been used up, the biofilm simply gets to work and starts regenerating its outer layer.
Before you know it, that layer is back. Ultimately, what this does is allow other bacteria that’s found in the water to regrow as well. The excessive growth of bacteria can eventually cause an extensive array of safety and quality problems in the water.
With the passage of time, you might notice the appearance of an oily ring on the water. This usually appears around the water line and doesn’t look good at all.
That’s not the only thing you will have to deal with; there’s also the issue of the water turning cloudy. If foam starts to develop in the water, that could lead to another problem as well.
To mitigate these problems, your primary option will be to add lots of sanitizer. That’s not all; you will have to focus on creating a chemical balance as well, which will ultimately increase the costs of maintenance.
Each month, you will find yourself spending a lot of money on chemicals. More importantly, the addition of excessive chemicals could create problems with the comfort levels in the water.
How To Clean Biofilm From Hot Tub
The best way to remove the biofilm is to make use of a strong pipe cleaning solution. You will have to add that in before you decide to drain the hot tub. You may want to activate the jets until the cleaning product has had a chance to run through the pipes properly.
This is going to ensure that the internal pipes in your hot tub are properly cleaned. There’s also the small matter of the filter, which should be cleaned using a powerful filter cleaner.
Thankfully, there are quite a few types of filters available in the market, and you may want to invest in a good quality one to ensure that the filter is properly cleaned out.
How to Prevent Biofilm From Building up in Your Spa
There are several enzyme based cleaners that you can use to keep the hot tub clean. You may want to invest in a good quality one and use it at least once a week or once a month, depending on your usage.

Hello, my name is David Zal and I’m a plumber with more than 20 years of experience based in Englewood (Florida). I like to teach normal people how to make easy fixes in their homes. I believe that a lot can be achieved just with DYI and that’s why I started this blog.