subject: How A Swimming Pool Sand Filter Works [print this page] One of the best ways to maintain your swimming pool in a clean condition is with a pool sand filter. This filter uses sand to remove debris from water. The sand that is contained in a tank or vessel and water is pumped through the internal distributor and in the tanks top. This permits to flow through the media. While the water is flowing through, the debris is removed from the water. The debris is held while the clean water is returned to the swimming pool.
This type of filter has a multi port valve which contains the following parts:
Filter: Used for normal vacuuming and filtering.
Backwash: Used to clean the filter bed of accumulated debris.
Rinse: Used after the backwash cycle is completed to make sure that all of the dirty water is then rinsed out from the tank.
Waste: This is for vacuuming heavy debris directly into the waste for lowering or draining the water level in the swimming pool.
Recirculate: Used to recirculate the water through the valve by passing the filter.
Closed: Shuts the flow from the pump to the filter off.
The internal parts of the filter include:
Vessel or Tank: The main body of the unit.
Top Diffuser; Permits the water in the pool to enter the tank and distribute the water inside the tank.
Media: This captures the debris from the water in the pool as it flows through.
Laterals: These are located under the media and permit the water in the pool to exit the tank and flow back to the pool.
Most sand filters have a valve, known as a multi port valve. This valve has numerous settings that direct the water flow in numerous directions. Backwash is one of these directions. When the valve is in the backwash setting, the water that is inside the tank is made to flow backwards. Rather than the water flowing from the top of the tank down, the pool water is fed into the bottom of the tank. The result is that the sand is churned and the debris is flushed out of the tank by means of a separate waste line. Most of these valves have a sight glass for so that this process can be viewed. While the water is being backwashed, a person can look at the water with a sight glass as it gets clean visually clean, the backwash is finished, the pump is stopped, and the valve is now placed into the rinse setting. After the pump is reenergized, the pump that is in the rinse setting permits the water to flow in the normal direction and this permits settling to occur in the tank.
