This is a Swimming Pool sand unit, typically with a backwash facility.

The filtration system removes organic waste on a daily basis should the pool owner configure their system in this way. by using the sieve baskets inside the skimmer, circulation pump and the sand unit with a backwash facility for easy removal of organic waste from the water circulation. Disinfection is achieved normally by using chlorine which kills infectious microorganisms. Alongside these two measures – pool owners should encourage swimmer hygiene and cleanliness that will help reduce organic waste build-up.