RESIDENCE swimming pools can be built with skimmer filtering systems or overflow systems:

SKIMMER SYSTEMS
Skimmer systems can only be used in swimming pools with a surface area of less than 100 m².
In swimming pools with skimmer filter systems the water level is about 15 cm lower than the edge, which collects water between the pool and the surrounding pavement area, as well as protecting the pool.
In this type of system, water is aspirated by skimmers, passes through tubes and filters and, once purified, is reintroduced into the pool through the supply inlets. The position and number of skimmers is determined by various factors, such as the size and shape of the pool, how exposed it is to dominant winds, the presence of devices like hydromassage nozzles or nozzles for counter current swimming and how close plants are to the pool.
This system is definitely simpler and less costly, but it does have some disadvantages, as it does not, for example, allow the whole surface of the pool to be cleaned.

OVERFLOW SYSTEM
Although a little more expensive than the skimmer system, the overflow filtering system has some hygienic, practical and aesthetic advantages.
In overflow swimming pools the water level is at the same height as that of the edge of the pool, making the pool look wider.
In this type of system, water comes in through the pool walls or floor, flows continuously along the edge or and flows into an overflow channel. It is then collected in a compensation tank, which allows the water level to remain constantly at the same height as the border. The water then passes through the filtering and disinfection group and finally returns to the pool through the supply inlets. The overflow channel is generally covered by a PVC grid, but in more elegant systems this is replaced by holed grid or border in various natural materials that underlines beauty of the system and does not alter its impact on the environment.

COMPENSATION TANK
The compensation tank, built below the level of the pool, collects the water that overflows the edge and enters the tube via the collection channel.
The compensation tank includes the following elements:
- a minimum level flotation device connected to the refill system
- a removal system for excess water
- a waste drain for emptying, cleaning and maintenance
- tubing from the swimming pool and filter group.
The compensation tank also recycles water for the treatment system: this is why it is essential that it is never completely empty, because otherwise it would operate without water and burn out the circulation pump.
The optimal volume for the compensation tank, fundamental for the functioning of the system, varies according to the size of the swimming pool and the capacity of the water treatment systems. It is generally 10% of the volume of the pool.