In the Protection stage, the bacteria colony or biofilm begins protecting itself against invasion. [chlorine resistant biofilm colony] Invasion from environmental factors, "lethal" chemicals (such as chlorine or bromine), predators, anything that want to destroy it. In technical terms, the bacteria begins to excrete a protective coating called an "exopolysaccharide" film. The film is sticky or slimy and very hearty. Now the biofilm is ready to experience explosive growth.

Growth of biofilms is like a coral reef, the biofilm gets bigger and tougher. Super colonies of biofilm are actually absorbing certain chemicals that were meant to destroy them. The chlorine or bromine may kill the out layers of the colony that are more susceptible to chlorine or bromine, but as the chlorine or bromine is exhausted, the lower, stronger, better protected layers are still living and multiplying. The good news is that as the biofilm colony increases in size, it gets more "unwieldy" and begins to break apart. That's also the bad news.

Now we come full circle to Distribution where these broken parts begin to attach to other surfaces or different parts of the same surface. And the cycle begins anew. Biofilms often lead to White Water Mold and Pink Slime.

By the way, biofilms are everywhere. Pools, spas, bathrooms, kitchens, the funky look to your patio furniture, on your teeth (plaque is a biofilm), wherever there is a surface that can be or is damp, you'll find a biofilm...guaranteed.

What to do? Resistant to chlorine or bromine. Bonds with biguanides. Ionizers have no effect. You have to remove it. But how?


Treatment & removal of Biofilms


Now that we know what biofilms are (learn about biofilms here), let's talk about HOW to remove them and prevent their return.

Biofilms can be removed mechanically, chemically or "naturally." 


Mechanical removal using vacuums, wall brushes, scrub brushes, filter cleaners, etcetera, physically remove the biofilm from visible places.

Visible places would be the filter cartridge itself, filter tank, vinyl liner, water line, ladder treads, [Wall whale pool brush helps to easily break up biofilms on pool surfaces] skimmer baskets, etc. You can physically handle the object that needs to be cleaned.  This is one of the reasons why we as Pool Professionals are so adamant about brushing the pool's surfaces on a regular, weekly basis.  Brushing breaks up and lifts the biofilm off from its cozy environs enabling the chlorine to kill it and the filter to remove it.  Be careful however to regularly clean & chemically clean the filter to remove the accumulations of "filtered" biofilms from the filter media - whether it be sand, DE or cartridge.


Aboveground pools with serious biofilm infestations should consider just changing the filter hoses. Typically, most aboveground pools have 2 - 9 ft. or shorter hoses as compared to well over 100 ft. of buried inground piping.

Keep in mind that biofilms are a direct contributor to chlorine demand, causing the pool to use significantly more chlorine, bromine or biguanides than if none were present.  Remove the biofilm, remove an important component to chlorine demand.

In hard to reach places like pool plumbing lines & inside heaters, biofilms need to be removed Chemically. This is where so much biofilm (and about 99% of the bacteria) accumulates and thrives.  Biofilm is left alone.  It has all that it needs - a surface, moisture, and nutrients floating by.


Keep in mind that biofilm doesn't need sunlight - it's not an algae so sunlight is not one of biofilm's needs. Biofilm does need "warm" water - 90 F or better for optimal growth, but as long as it's not cold, the biofilm will survive and grow just fine thank you.

Tried & true products such as natural enzymes (NaturCare Enzymatic Cleaner, Pool First Aid, etc.) "eat up" (Natural removal) much of the nutrients and other waste that contribute to biofilm growth thereby stunting it. But as biofilms become more resistant and more proliferate, a new arsenal of products must be considered & used.  Newer products such as AquaFinesse™ Pool Water Care Tablets are added to the pool skimmer and quite rapidly remove the biofilm from the hidden surfaces.


All of those films or slimes are what we call biofilms. In biofilms live the other roughly 99% of all pool bacteria. The 1% that is in the water freely floating around is classified as "planktonic". Like plankton or algae, planktonic bacteria free-floats in the water. That is the bacteria that your chlorine, bromine or other sanitizer can "easily" kill. The 99% of the bacteria in the biofilm can be quite another story and long-term headache. There is much information about biofilm from institutions around the world to back up our information to you. Montana State University's Center for Biofilm Engineering is one of our key sources.

First, what is a biofilm? A biofilm is a film or large quantity of bacteria that is living in and as a vast colony in the microscopic world. In the "big" world, you could call a coral reef a "biofilm." A biofilm is self-perpetuating and difficult to remove. Worst of all, biofilm love virtually any surface, especially wet or damp. But beware, even after drying out, the biofilm will not necessarily be dead but simply dormant. Did we mention that biofilms are relatively resistant to chlorine, bromine or other sanitizers?


Second, how do biofilms form? As just mentioned, biofilms form on any surface. In your pool that means the liner or the pool walls, bottom, ladder rails, skimmer baskets, ladder treads, filter tank bodies, pump bodies and impellers, directional returns (eyeballs), heater plumbing, and especially the piping. There is a 5 steps process as to the formation of biofilms: Attachment, Colonization, Protection, Growth, and finally what I call Distribution.

Biofilms in swimming pools can and often do lead to cloudy water, algae blooms, scale build-up on the heater (prevents efficient heating), and even corrosion (certain biofilms can have a pH of about 1.0 - very acidic) of any metal surface of the pool system including heaters, filter parts, ladders, rails, etc.


Much of the biofilm found in swimming pools is hidden away in pool plumbing & the filter system. The average residential inground pool can easily have 150 - 200 lineal feet of piping!


Commercial or semi-public pools can have many times that.

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Biofilms... they're nothing new...
If you think your pool water is clean and sanitary just because it looks clear, think again. Yes, you may have shocked the water and added algaecide and even maintained a good chlorine, bromine biguanide (Soft Swim or Baquacil) level, but you've only controlled about 1% of the bacteria in your swimming pool!


That's right, just 1%. The other 99% is on every pool surface that you can or can not see. And most of those places are virtually impossible to reach. What now?


The more we deal with swimming pools and pool problems, the more we realize that we're dealing with or treating symptoms rather than the root cause of the cloudy water, algae, scale build up, etc.


For complete information, visit us at PoolMoldSolutions.com

Here's the inside of a filter body. Notice on the left that it's covered in sticky, icky biofilm. On the right, just having the pool treated with AquaFinesse, the biofilm has been removed.

Two examples of how dramatically AquaFinesse™ Pool Water Care Tablets removes bacteria laden, ugly Biofilm
although the water is clear, notice the "black" grout lines turn white

Not to mention chlorine or sanitizer demand, excessive need for shocking and so on. As I've noted in other articles, there are a plethora of reasons for cloudy water from poor water chemistry to poor circulation to improper cleaning habits to environmental causes. And typically, these causes combine to create the problem.

As we look for the root cause, we see more and more that there are real "problems" that are often undetected. What do we mean? Have you noticed that there is a regular build up of film on the pool liner, up and down the walls or in the corners? If you are a regular brusher, the problem may not be as noticeable. How about when you take the filter apart for normal maintenance or cleaning and you see a whitish film on the inside of the tank or on the skimmer weir or skimmer body?

Attachment is just that; the bacteria attaches to the surface. It wants a place to call home and grow. Bacteria want to be in relationships, so that find a nice surface to settle down and join up with a few of their closest friends.

After attaching to the pool surface with their friends, Colonization takes place as bacteria multiply and divide, growing in number. According to studies, it is at this crucial point that this attachment is "irreversible." The bacteria colony is there to stay unless purposefully removed. This stage is typically accomplished in a matter of minutes or hours at most.


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Swimming Pool Biofilms...

AquaFinesse™ products have been successfully used in the European market and in industrial applications for several years. As with the physical removal products, loosened & removed biofilm particles must be filtered out of the water then removed from the system entirely.  After initial application, you will notice that the filter becomes rapidly clogged as the filter traps all of that used biofilm.  Cartridge and diatomaceous earth filters must be chemically cleaned to restore the filter to a proper working condition.  If biofilm removal has never been done before, it may be necessary or even advantageous to replace the filter media - especially in older swimming pools.  These products are completely compatible with all pool care chemical systems (chlorine, bromine, biguanides, ionizers. salt) Click here to purchase.