A modern swimming pool is based on water re-circulation, completed by filtering and decontamination. The water is aspired of the surface layer with a pump, using special pieces set up in the swimming pool walls, named skimmers, and the deep layer suction si made by a main drain. Afterwards, water passes through a filter that retains impurities and returns in the pool by inlet nozzle installed in the walls.

The decontamination and heating equipments are installed in the technical space on this close circuit of the swimming pool water.

The swimming pool pump functions under the control of an automation board containing a programming watch.

In order to have clear and clean water, two treatments of mechanical filtering and chemical decontamination are required. The filtering ensures the removal of the impurities, while the chemical decontamination ensures the destruction of the bacteria, algae and microbes.

The filtering process has an important role in the obtainment of quality water; it retains the organic and mineral impurities and thus the decontaminating products can be efficient.

It is considered that 80% of the water quality is obtained by the correct projection and execution of the filtering circuit; it is recommended that the slumps should be on the wall opposite to the skimmers and that should be a sink water trap.

Some impurities are heavier than water and they will fall on the swimming pool bottom. The must be removed by here by using a vacuum. It can be manual, automatic or a robot type. The latter two variants spare your time and effort; all that is left to be done is emptying the robot sack or cleaning the swimming pool filter.

There are three types of filters:

a) Quartz sand filter: is the most encountered the easiest to clean, perfect for the outdoor swimming pool. It can retain impurities of up to 30 microns. For smaller impurities, one must use flocculants (a substance that determines the aggregation of small particles into "balls" of such sizes as to be retained by the filter). The sand should be replaced every 2-3 years.

b) Scroll filter: resembles the air filters of the cars, It has a great filtering keenness (it retained impurities of up to 5 microns). This is why it also clogs rapidly. Do not use flocculants! It must be replaced annually.

c) Diatom filter: resembles the sand filter, but as opposed to it, the diatom (small fossil shells) has the greatest filtering keenness. It is more difficult to exploit. Do not use flocculants! The diatoms are completed as they are consumed.