How Common is Biofilm in Pools and Hot Tubs?

If you’ve found yourself with biofilm buildup in your pool or hot tub, no need to fear, this is a fairly common occurrence that many pool and hot tub owners experience at some point along their ownership journey. Biofilm buildup is common enough that companies have created a variety of cleaning products that are readily available to help you treat and prevent these buildups before they become maintenance issues. 

If you have been lucky–or diligent–enough to avoid biofilm buildup thus far, it may still be a good idea to read up, as a biofilm takeover may be waiting to strike as soon as you let your guard down. 

What is Biofilm?

Biofilm refers to any buildup of microorganisms–such as bacteria–that live on underwater surfaces. As biofilm starts to build, these underwater surfaces may start to become slimy–a phenomenon many pool and hot tub owners recognize all too well. 

For the most part, biofilm is harmless, it is actually a part of our daily lives; however, a buildup in your pool or hot tub can eventually lead to unwanted smells, maintenance issues, and potential health hazards. For these reasons, it is advised that you take preventative measures and begin treatment right away if any biofilm is detected. 

If you would like to know more about biofilms, here is an educational article from the National Library of Medicine that gives in-depth information. We recommend giving it a read!

How to Treat and Prevent Biofilm Buildup in Pools and Hot Tubs 

Thankfully, there are several available cleaning products on the market that will help treat biofilm buildup, should it occur. The next step is choosing the right products for the job. 

For pools, we recommend this swimming pool water clarifier and bio-cleaner designed to both prevent and treat biofilm buildup in pools. Before using a bio-cleaner, it is important to test your pool water’s pH and total alkalinity and adjust accordingly. 

The biofilm living in your hot tub is likely comprised of different organisms and care products, this hot tub cleaner is better designed for warm-water environments and is formulated to clean within the jetted lines to prevent and treat any buildup lurking there. For more serious cases, a purge cleaner may be necessary to thoroughly clean all of the nooks and crannies associated with a hot tub.  

It can also be helpful to scrub the biofilm scum off of visible surfaces to help the chemical treatment do its job, ScumRays will do the trick. These effective–and cute–scrubbing pads not only break up scum but also absorb oils and lotions, which can contribute to biofilm issues. 

Can Biofilm Damage my Pool or Hot Tub?

With time, biofilm buildup may cause damage to your pool or hot tub. The biofilm itself isn’t necessarily the direct source of damage; however, an excessive buildup can cause your equipment to run inefficiently, eventually leading to failure if not treated early enough. This is particularly true for pool and hot tub filters, pipes, and jetted hot tub lines. 

Biofilm buildup in these areas is potentially damaging because it can restrict the water flow. When the water flow is restricted, the equipment moving the water will have to work harder to keep up with demand. Overworked equipment is likely to wear down much faster than it would have normally, leading to increased maintenance and replacement costs. 


Biofilm buildups are, unfortunately, a common occurrence in pools and hot tubs. However, there are simple ways to treat and prevent biofilm from becoming a larger issue. The routine use of prevention products, along with using the best treatment products when needed, will keep your pool or hot tub clean and running smoothly. 

2 Comments. Leave new

  • hi: I have a yellowish, very sticky scum line that has appeared in my hot tub. Can I deal with this issue with your product? I’ve tried using common cleaners – baking soda, vinegar, CLR, even methyl hydrate (methyl alcohol) Nothing seems to dissolve it or get rid of it. HELP!! thanks

    • Good morning. Yes, this is what we call biofilm. Very easy to deal with by using one of our Ahh-some Hot Tub/Jetted Bath Plumbing cleaners. We sell this product in 4 different sizes. I would recommend getting either the 2 oz or the 6 oz size. Very simple to use. Simply add the required amount of gel to your hot tub (1 teaspoon per 125 gallons of water) and run the jets on high for 30 minutes. Remove your filter cartridges from your filter compartment and set them off to the side. My email is [email protected] and my cell number is 701-412-1267 if you have any additional questions or if you are having difficulty finding the particular Ahh-some products.


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