What Is a Pool Sand Filter? As the name suggests, a pool sand filter uses sand to filter pool water. The water passes through a chamber filled with sand, trapping particles, debris, and other contaminants. The purified water flows out of the sand filter and back into the pool. Using sand for water filtration dates back to civilisations as early as 2000 B.C.! In the last few decades, sand filter technology for swimming pools has become more popular because it works well and costs less than other pool filters. A pool sand filter uses silica, quartz, or garnet. These natural materials are proven to trap dirt and debris from water. They also help to improve water clarity and reduce chemical usage in pools. The ancient use of natural materials to filter water can give you confidence that a pool sand filter is an excellent choice for keeping your swimming pool clean and safe for the whole family to enjoy! How Pool Filters Work Pool filters trap dirt, debris, and other contaminants in pool water. How? Pool water enters through an inlet pipe into the filter tank. Contaminants are trapped as the water flows through the filter media (or material). The clean water exits through an outlet pipe at the bottom of the filter tank. How does a pool sand filter work? Silica sand (the most commonly used sand for pool filters) is made up of hard, angular granules that are incredibly effective at trapping and filtering particles from water. Silica sand can filter particles down to 20 microns (approximately 0.0008 inches). A pool sand filter has several settings and controls that regulate its operation. Pressure gauge. Measures the water’s flow rate, or pressure, as it enters and exits the filter tank. Multiport valve. Multiple ports inside this valve allow water to move in various directions for cleaning or backwashing. Timer. Controls how often the filter cycles. You can determine if your pool sand filter is working by checking the pressure gauge. The pressure reading (PSI) should be between 10 and 25. The normal operating pressure of your pool depends on how big and powerful your pump is and how clean your filter is. If the pressure is 10 PSI higher than usual, your filter needs cleaning through backwashing. If the pressure is 5 PSI lower than usual, water isn’t flowing through the filter quickly enough. Most likely, there is a blockage somewhere before the filter. Make sure no leaves, twigs, or other debris is blocking your skimmers, drain covers, pump basket, or impeller. You can also check to see if your filter is working properly by looking at the water. Your filter needs attention if there is a buildup of dirt and debris in your pool. By understanding how pool sand filters work, you can make an informed choice for your swimming pool filter.