An in-floor cleaning system is designed prior to the swimming pool being constructed or manufactured, depending on the pool interior. In consists of a series of heads that pop up in the floor and steps of the pool. This is not dissimilar to pop up heads in your garden sprinkler system.
Their purpose is to drive the dirt and debris towards a drain point, usually located in the deep end of the pool. Once the dirt is removed from the drain point by the pump, it usually passes into the filtration system where it will get trapped.
In leafy pools, there is an additional primary straining point, which catches the heavy leaf matter before the filtration. Every system must be designed individually as every pool is usually a different shape and size. This system also aids in chemical distribution and heat circulation throughout the entire pool. Some systems rely solely on the filtration pump to drive them and others require a separate pump to operate the cleaning system.