Every pool must be cared for so that it is clean, hygienic and so that swimming is enjoyable. Filtration equipment retains some contamination and must therefore be inspected, but no filtration equipment guarantees 100% water purification. Bacteria, algae, fungi, pollen, fine dust, skin particles are too small to pass through the filter. In addition, bacteria, algae and fungi spread in the water, which cover the walls of the pool with a slippery thin green layer, which is an ugly sight. For this reason, the development of algae, bacteria and fungi should be prevented and combated.