Sand filters must be backwashed in order to loosen up the sand and to eliminate filtered dirt through the waste system. This requires, among other things, that the hydraulic action of the filter circulation pump be reversed through the filter housing.
Multiport valve operation:
FILTER: In this position the pool water is pumped into the filter where sediment and dirt are trapped in the sand bed, allowing only clean water to return to the pool.
BACKWASH: In this position the pool water is pumped into the filter, dirt and collectable particles in the sand bed are dislodged and washed down the waste line. Backwash the pool for approximately 3-5 minutes or until the water, visible in the sight glass on the side of the Multiport valve becomes clear.
RINSE: In this position the pool water is pumped through the filter down the waste pipe. This position is used immediately after backwashing to rinse and settle the sand before switching on the filter approximately 3 minutes after every backwash. After backwashing, fresh water must be fed into the system in order to re-establish the original water level.
RECIRCULATE: In this position water from the pump will bypass the filter sand bed.
WASTE: In this position the pool water is pumped through the multiport valve direct to the waste line, bypassing the sand bed. This position can be used when the pool has a large buildup of dirt and leaves and alleviates the necessity for backwashing after vacuuming. Waste position should only be used for short periods as large volumes of water will be pumped down the waste line which may result in the pool water level falling below the skimmer level.
CLOSED: In this position the multiport valve is closed off and water from the pump will not pass through the filter. This position should only be used when cleaning the primary strainer.
NOTE: Any time you move the handle on your multi-port valve to switch positions or settings you must first turn off your pump. Keeping the pump running while moving that handle can cause you to blow the gasket in your valve. Not an expensive fix, but a fix you can avoid. Do not operate the pump with the valve in the closed position or when turning to a position on the valve.