When we treat our pool water, we often focus on suspended bacteria (planktonic bacteria). Yet these are rarely the cause of health problems. The real culprit is biofilm.

Biofilm is a thin organic layer that settles on submerged surfaces such as walls and pipes. Once formed, it becomes an ideal refuge for a massive concentration of bacteria. As it grows, biofilm fragments break off and, if accidentally ingested, can cause digestive disorders and other discomforts.

Contrary to popular belief, chlorine does not destroy biofilm. It only acts on the bacteria released into the water, treating the symptoms rather than the cause.

What can be done to tackle the problem at source? Regular wall cleaning, pipe maintenance and proper water filtration can eliminate biofilms before they become a problem. These efforts, combined with optimized chemical management, can significantly reduce your chlorine consumption.

Some professionals use chlorine dioxide (𝐶𝑙𝑂₂) to radically eliminate biofilms, ensuring long-lasting disinfection in just a few months.