How Does Inground Pool Filter Equipment Work?

Filter Types

• The sand filter uses No. 20 silica sand to trap dirt particles during the filtration process. The sand is replaced every one to five years, depending on the usage of the pool.

  Cartridge filters use a pleated cartridge to capture dirt particles. Cartridges are cleaned by rinsing the cartridge off with a garden hose. Cartridges are replaced once a year under light usage or more often if the pool has heavy usage.

  DE pool filters use diatomaceous earth powder and a grid to filter the water. It works similarly to the sand filter, but the powder coats the grid so it can capture the tiny dirt particles.

Water Flow

• The water flows into the pump through the intake piping. The water passes through the sand, DE grid or cartridge, where the small dirt particles are trapped. The water then flows out of the pump through the outflow piping and back to the pool. Generally, a home pool is filtered twice a day for eight hours each time. The pool filters once during the daytime, and once at night while the pool is not in use. Some public pool operators will run the filter continuously to keep the water clean due to the heavy usage.

Skimmer Baskets

• Skimmers work with in-ground pool filters to remove large pieces of debris that float on the top of the water so that the pool filtering system can remove small particles from the water. Skimmer baskets are located just under the pool deck under a protective cover. A smaller skimmer basket is located on the side of the pool pump just after the water intake and before the water goes into the filter, to catch debris that may have come though the underwater filtering drain. Skimmer baskets will move up and down to draw in water and filter out dirt when the pool filter is in "Filter" mode.

Multiport Valves

• Multiport valves control the operation of the in-ground pool filter. Typically, these have settings including "Rinse" for rinsing the pool filter, "Backwash" for cleaning out the dirt particles captured by the DE or sand filter, and "Filter" for running the pump at pre-selected times. Some valves have "Waste" for removing water from a pool to the backwash hose without going through the filter, and "Vacuum" for vacuuming the pool water. Valves may have a "Winter" or "Stop" mode, which is the position for winter months when the pool is usually not in use. Some will have "Recirculate," which moves water through the pool system without filtering.