Solids can be dispersed into the swimming pool water in various forms. The nature of such dispersions depends on the size of the particles. In general, it is possible to remove these floating or suspended solids (up to 0.001 mm in size) from swimming pool water with effective filter systems. Every swimmer brings colloidal pollutants into the pool water, such as bacteria, germs, cosmetic residues, etc. These substances, with a size between 0.1 and 0.001 micrometer, are spread in the pool water during swimming and are not directly visible to the human eye. Such contaminations can become visible when there are spotlights installed in the pool in the form of turbid water. Even highly effective filter technology cannot completely remove this contamination, which can lead to an increase in bound chlorine. This can lead to an organic overload in the pool. By using flocculants or flocculants, the dirt particles will clump together into larger flakes, so that they are large enough to be caught by the filter system. Aluminium and iron salts are often used in a flocculant so that the insoluble aluminium hydroxide forms a floc that will precipitate out, removing the colloidal particles from the wastewater.