It is the most classic type of pool where water is recycled through surface hoods (skimmers). It does not require the construction of an additional tank or overflow channel and for this reason it has an economic advantage. The level of the pool is set by the surface hoods lower than the height of the perimeter walls, thus emphasizing the characteristics and location of the pool in the surrounding area while offering a sense of greater security. In terms of cleanliness requires good design of hydraulic characteristics to ensure uniform circulation on the surface and avoid the creation of stationary points.