Changing pool filter sand involves shutting off equipment, removing the multiport valve, carefully extracting old sand, and adding new #20 silica sand in layers while avoiding damage to laterals.
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Before diving into the replacement process, confirm your sand actually needs changing. Pool filter sand typically lasts 5-7 years, but several signs indicate earlier replacement: consistently cloudy water despite proper chemistry, shortened time between backwashing (less than 2 weeks), visible channeling in the sand bed, or sand returning to the pool through return jets.
If your sand is less than 3 years old and you're experiencing filtration issues, the problem might be improper water chemistry, damaged laterals, or a cracked multiport valve rather than the sand itself.
Turn off your pool pump and ensure the system is completely shut down. Never work on pool equipment while the pump is running - this can cause serious injury. Close any valves that might allow water to flow back into the filter tank.
Disconnect the pressure gauge and any plumbing connections to the multiport valve. Most valves are held in place by a clamp ring - loosen this carefully as the valve can be heavy. Some older systems have unions that need to be unscrewed. Mark the valve position with tape before removal to ensure proper reinstallation.
Important: Be extremely careful not to damage the standpipe (center tube) during valve removal. A cracked standpipe will require professional repair.
Before removing sand, tape over the top of the standpipe to prevent sand from falling into it. The laterals at the bottom of your filter are fragile plastic components that can crack if sand falls on them with force. Consider adding a small amount of water to the tank to cushion any remaining sand.
Use a shop vacuum or specialized sand removal tool to extract the old sand. Work systematically from top to bottom, being careful not to disturb the laterals at the bottom. Wear a dust mask during this process as silica dust can be harmful if inhaled.
As you reach the bottom layers, work more carefully. You may encounter calcified or cemented sand that requires gentle scraping with a pool brush. Never use sharp tools that might damage the tank or laterals.
With sand removed, inspect the lateral assembly for cracks or damage. Each lateral should be firmly attached to the manifold. Replace any damaged laterals now - it's much easier than doing this job again in six months.
Check that the standpipe is straight and properly seated. A bent standpipe will cause uneven water distribution and poor filtration.
Add water to the tank until laterals are just covered - this cushions them during sand addition. Pour new sand slowly and evenly, using a pool brush to distribute it and prevent channeling down the standpipe.
Add sand in 50-pound increments, leveling each layer before adding more. Most residential filters require 200-300 pounds of #20 silica sand. Only use #20 silica sand - never use play sand, masonry sand, or other substitutes as these can damage your system.
Fill to about 6 inches below the top of the tank, ensuring sand level is even around the standpipe.
Remove tape from the standpipe and carefully reinstall the multiport valve, aligning it with your reference marks. Tighten the clamp ring evenly to prevent leaks, but don't overtighten as this can crack the valve body.
Reconnect all plumbing and the pressure gauge. Double-check all connections before proceeding.
Fill the tank completely with water through the pump strainer basket - this prevents air pockets. Set the multiport valve to "Rinse" and start the pump. Run for 2-3 minutes until water runs clear, then switch to "Backwash" for another 2-3 minutes.
Finally, set to "Filter" mode and run normally. Expect slightly cloudy water for 24-48 hours as the new sand settles and fine particles clear.
If you experience sand in your pool after replacement, check that laterals weren't damaged during installation and that you used the correct sand grade. Excessive pressure readings might indicate sand was added too quickly, creating air pockets - try backwashing to resolve this.
Poor filtration immediately after sand change is normal for 1-2 weeks as the sand bed conditions itself. However, if problems persist, verify your pool chemistry is balanced according to TFP standards: FC appropriate for your CYA level, pH between 7.4-7.6, and proper TA levels.
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