The sand filtration systems are the most common and simple to use, very acknowledged and have a low maintenance schedule.
They use sand as filter medium. When filters are used to clean poolswater, filters work in pressure and the flow is descending (down flow, from the top to the bottom). Solid materials are gradually held back while the water pass through the granulated materials stratum. Over time, the filtered material held by the filter create an obstacle at the passage of the water and made the filtration less efficient.
For this kind of filters is therefore indispensable to periodically stop the water filtration and clean the filter (backwashing). This operation requires a lot of water. Furthermore they have an average filtration quality (20/30 micron) and the filters require relevant spaces.
Simple management and low maintenance
Filter material easy to find
With coagulation and flocculation the filtration quality improves.