What Causes Slime In A Hot Tub?


Slime in a hot tub is formed by the build-up of bacteria and microorganisms caused by insufficient sanitation.

Unfortunately, people usually neglect their hot tubs trying to limit the use of sanitizers, particularly chlorine, which enables bacteria growth that cover themselves in a protective layer called biofilm, producing a slimy, odorous substance that is very difficult to eradicate. Moreover, that substance can cause many troubles to the hot tub, such as cloudy water, floating grime, clogging its pipelines, and some health issues with people.

Biofilm is a living organism that usually grows undetected in hot tub’ plumbing because of the dark, warm and moist environment that allows it to thrive. Still, sometimes it could be felt on the hot tub’s interior, too.

Suppose you neglect your hot tub maintenance by using less sanitizer than necessary, changing and cleaning your filter irregularly, or keeping your water more standing than circulating. In that case, your hot tub becomes fertile soil for bacteria growth. Body oils, lotions, cosmetics, sweat, etc., are practically the base for creating biofilm, allowing it to come to life and spread on its own, which eventually reduces the effectiveness of sanitizers and increases the water’s acidity levels.

Thus, any hot tub that is improperly sanitized or rarely maintained becomes susceptible to slime growth. Therefore, it is of great importance to take care of your hot tub’s health to avoid issues that could arise from such neglecting.

How do I know if my hot tub has biofilm?

The appearance of the turbid water, which has an unpleasant smell and a high level of acid, means that your hot tub is suffering from biofilm growth.

Biofilm is a colony of bacteria that has a higher level of resistance to sanitizers than other bacteria found floating in the water have. Moreover, this living organism reduces the effectiveness of sanitizers such as chlorine or bromine, thus increasing the water acidity and lowering the alkalinity.

Sometimes biofilm is seen on your hot tub interior, and you can feel that slimy, slippery substance. On the other hand, it stands hidden in your pipes long before you even notice you have the biofilm problem. The first indication that you have slime in your hot tub is a low chlorine level or other sanitizers, even if you use more doses than usual. My recommendation that proved highly useful for testing water is the TAYLOR K-2006 test kit that is very precise in testing your water for chlorine, PH, alkalinity, calcium hardness, etc. Additionally, if there is an insufficient sanitizer, your water will soon become foamy because of the contaminants.

Poor filter maintenance or rare water circulation will lead to forming a biofilm. For example, if you are not using your hot tub for a more extended period, you will notice white flakes in your water when running jets, followed by an unpleasant odor. Those flakes are slimy and icky in the water, but they turn solid hard like a rock when dry

Can hot tub biofilm make you sick?

Biofilm is a colony of different types of bacteria, and the longer someone is exposed to it, the greater the chances that they are getting sick.

In addition, the build-up of bacteria causes high acid levels in the water that can cause skin irritation, such as skin rash.

On the other hand, it gets far more severe if you happen to swallow contaminated water. Biofilm can consist of many harmful microorganisms that can lead to serious health issues once you get in contact with them. Bacteria such as Legionella, which causes Legionnaires Disease, and Escherichia Coli, are possible microorganisms that lead to pneumonia, painful stomach aches, and urinary tract inflammation.

Another bacteria, among many others, commonly found in slimy biofilm is Pseudomonas which usually attacks people with a weakened immune system or have some other illness that is deteriorated by the bacteria.

Suppose you find that you have biofilm issues in your hot tub. In that case, you need to take necessary measures immediately to eliminate the problem because it can seriously disrupt your immune system.

How To Get Rid of Hot Tub Biofilm?

To get rid of the biofilm substance, you will have to clean your hot tub thoroughly with hot tub cleaning products; the interior, the plumbing, and filters.

Biofilm is a protective, slimy layer that forms over the colony of bacteria and protects them from regular sanitizers such as chlorine or bromine, making them ineffective in eradicating hot tub contaminants. Being unable to keep your hot tub clean and sanitized, you will have to use other cleaning products other than chlorine or bromine.

Due to improper and insufficient maintenance, unbalanced water, and neglected filters, your hot tub becomes susceptible to bacteria growth. Accordingly, the first step towards cleansing your hot tub from biofilm is cleaning filters. If your filters are already old and worn out, it would be better if you replaced them. However, if they are still usable, you should wash them thoroughly and soak into filter cleaning products and leave them overnight for best performance.

The next step is to get rid of the formed biofilm. To do that, you should use some highly penetrating product that eliminates the biofilm from your hot tub effectively, especially from the plumbing. Many products on the market are specialized in that, but the one I find most effective is “Ahh-some.” This cleaner works better than any other available on the market. You should run the cleaner through the hot tub system and make it circulate for some time. After running it through jets and other plumbing, the cleanser will remove hard biofilm deposits, and you will see them floating in your water.

You should drain the hot tub afterward and clean the interior with a disinfectant before refilling. Once you refill the hot tub, you should balance its chemistry and do the chlorine sanitation.

However, sometimes it is necessary to repeat the procedure if you neglect your hot tub for an extended period because the biofilm is hard to kill, especially if it is not treated in time.

After you finished cleaning and disinfecting your hot tub, it would be best if you used the TAYLOR K-2006 test kit to check the chlorine levels. If the chlorine level is still low, it is possible that you still have some biofilm left in your pipeline and that you should repeat the process once again.

How To Prevent Hot Tub Biofilm?

Properly sanitizing and maintaining your water can prevent hot tub biofilm growth.

Depending on the number of people and how often they use the hot tub, you ought to drain and refill your hot tub every three to four months on average. Before draining, it would be best if you used some cleaning product that penetrates inside your plumbing and hard-to-reach places. To ensure that your hot tub is free of any organic, mineral, and chemical contaminants, you should opt for Spa Marvel Cleanser, which will effectively keep your hot tub clean and without unpleasant odors. This product might also prolong the period between drain and refill.

 Additionally, be advised to take care of your filters, too. You should take out hot tub filters once a week and give them a thorough cleaning, and at least once a month, soak them in some chemical cleaning product and leave it overnight to eradicate any possible biofilm forming. If your filters are all worn out, replace them with new ones to have more effective performance.

From my personal experience, I find that O-Care – Weekly Spa Water Care Pack is the best solution to keep my hot tub clean from any invisible threats that could endanger my water’s cleanliness or sanitation. Using the recommended amount of this product once a week successfully prevents biofilm growth and keeps my water clean and clear. On the other hand, it would be essential to shock your hot tub after every heavy use.

Can you get rid of biofilm without draining the hot tub?

Biofilm is a substance that is very hard to eradicate; hence if you want to make sure that it does not form again, you have to clean your hot tub and drain it afterward thoroughly.

Moreover, if you happen to neglect your hot tub for a longer period, you might need to repeat the process of cleaning and drain and refill your hot tub again.

In some cases, if you find the hot tub biofilm only on the interior, you can wipe it out with the disinfectant tissues. Sometimes biofilm is visible, and you can feel that slimy substance when you enter the water. However, other times, it keeps hidden and thrives in your plumbing, and you do not see it unless you run your pumps using some effective cleaning product for pipes. If your tub’s plumbing is indeed infected with biofilm, white, slimy flakes will appear floating in your water. 

The best possible option is to treat it with some highly effective cleaning products. First, put the cleaning solution in the water and turn the jets on for several hours. Once the product has reached every possible corner of your hot tub, drain it and refill with fresh water and make sure that you sanitize it properly to prevent the biofilm from regressing.

Does vinegar kill biofilm in hot tubs?

Vinegar is a homemade natural product proven highly efficient all-purpose cleaner, even with the hot tub biofilm.

Since vinegar is a pure natural product, it is safe to use and treat different types of materials. It successfully removes bacteria, limescale in the water, clogs in hot tub jets, and other water residues. Vinegar’s acidity PH levels range from two to four, making it possible to dissolve hard, grim deposits and soap scum from your hot tub interior and plumbing without harm or damage to the materials.

As previously stated, vinegar is the best solution to get rid of the hot tub bacteria growth. Hence, this solution can be used to clean the filters, too. Use equal amounts of water and vinegar and soak the filters for a couple of hours.

In addition, mix equal amounts of water and vinegar in the spray bottle and disperse the solution all over the hot tub. The process will effectively sanitize your interior without any harm to the environment. To rinse, use a sponge, gently clean the inside and bottom of the tub, and use a dry cloth to wipe it down, making it sparkling shiny.

However, even though vinegar proves to be such a powerful cleaning solution that even degrades the colony of bacteria called biofilm, you would need a lot of it. You would have to leave it in your pipes for 24 hours to dissolve the biofilm.

Editorial Staff

I'm Adnan Sabanovic, the guy behind Hot Tubs Report. I've had a chance to enjoy hot tubs last few years and have really become interested in owning one of them. Nearly every weekend you'll find me spending time with my family or playing sports. If I am not doing that then I'm here writing about tubs on Hot Tubs Report. This blog is a research for my first hot tub which I decided to document and share publically so others can benefit from it as well.

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