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! Yes, just 1%. Where’s the other 99%? 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. 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?
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 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% 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 my information to you. Montana State University’s Center for Biofilm Engineering is one of our key sources.
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.
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.
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.
In the Protection stage, the bacteria colony or biofilm begins protecting itself against invasion. 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.
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 and come to Distribution where these broken parts begin to attach to other surfaces or different parts of the same surface. And the cycle begins anew.
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 damp. You can view a video on swimming pool biofilms at our blog by clicking on the link below.
Keep in mind that all biofilms are not bad. How? Some are being used in industrial situations to plug microfissures. But in pools ans spas, we don’t want them.