Sand filters are one of the most common types of pool filters and work with both salt water pools and chlorine-based pools. Sand filters work by allowing pool water to pass through them but preventing debris from passing through, thus filtering the water. The result is crystal clear water for swimmers to enjoy. A standard sand filter removes particles and debris up to 40 microns in size, and filters 15 to 20 gallons of water per minute. The great thing about sand filters is that they actually improve in efficiency over time, because the debris that it traps actually begins to block out debris as well.
Monitor the pressure gauge reading for the pool on a weekly basis. When it displays a pressure reading of 8 to 10 lbs. over the initial clean reading, you must clean the sand filter.
Backwash the sand in the sand filter once every four weeks. Backwashing is cleaning the debris out of the sand by reversing the flow of water. First, shut off the pool's motor pump. If your pool filter has a slide valve, grab the handle and twist while pulling upward to a height of approximately 3 inches. If your pool filter has a multiport valve, push down on it and turn it to the "Backwash" setting. Open the air bleeder hose on the filter and turn the pump motor back on. After the hose fills with water, run it until the water is clear and then shut the pump motor off. If you have a multiport filter, additionally you must turn the filter to the "Rinse" setting and rinse for approximately 15 to 30 seconds. Return the filter dial to the "Filter" setting.
Every seven to 10 years replace the sand in the sand filter. Empty the water from the filter by removing the drain plug and allowing it to drain out. When draining is complete, remove the top dome (for slide valves) or the multiport valve. Use a scoop to remove all of the old sand from the filter. Alternatively, you can use an industrial strength vacuum cleaner to suck the sand out. Use a garden hose to rinse out any sand particles left in the filter and then add a small amount of water to cover the laterals at the bottom of the filter. Pour new pool filter sand into the filter up to the level recommended by the filter manufacturer (usually about 75 percent). Close the filter back up and backwash the sand twice to remove any dust. Return the dial setting to the "Filter" position and begin using the pool as normal.