Replacing sand in a Hayward pool filter takes four to six hours and costs $30 to $80 for the sand itself

The sand inside your Hayward filter traps dirt and debris as water passes through it. Over time—usually one to three years depending on how often you use the pool—the sand becomes clogged and stops working well. Backwashing (reversing water flow to rinse the sand) helps temporarily, but eventually the sand needs to be replaced entirely. You can do this yourself with basic tools and no special skills.

The process involves draining the filter tank, removing the old sand, cleaning the internal parts, adding new sand in the correct layers, and reassembling everything. Hayward makes several filter sizes, so the exact steps vary slightly, but the principle is the same for all of them.

Key Takeaways

  • Turn off the pump and filter system completely before opening the tank, and leave the system off until you finish and refill with water.
  • Hayward filters use layers of sand and gravel in a specific order: gravel on the bottom, then sand, then smaller gravel at the top—use the same layers when refilling.
  • The sand you buy must be pool-grade silica sand, typically labeled as 20-grade or similar; do not use play sand or construction sand.
  • After refilling with sand, run the filter in backwash mode for three to five minutes to settle the sand and remove air pockets before returning to normal operation.

What you need before you start

Gather these items before you open the filter tank. You will need a wrench or socket set (usually 1 1/16 inch or 1 1/4 inch, depending on your Hayward model) to loosen the bolts holding the tank together. A wet/dry shop vacuum makes removing old sand much faster, though you can scoop it out by hand with a bucket. A garden hose with running water is essential for rinsing the tank and internal parts.

Buy pool-grade silica sand in 20-grade size—this is the standard for Hayward filters. The amount you need depends on your filter size. A 24-inch Hayward filter typically holds about 200 pounds of sand, while a 19-inch holds about 100 pounds. Check your filter's manual or the Hayward website for your exact model's sand capacity. You will also need a bucket, a measuring cup or small container, and a helper is useful but not required.

Draining the filter and removing the old sand

Turn off the pump and filter system at the breaker or switch. Open the drain plug at the bottom of the filter tank—it usually has a handle you can turn by hand, or you may need a wrench. Let all the water drain into a bucket or onto the ground. This takes 10 to 20 minutes depending on how much water is in the tank.

Once the tank is empty, unbolt the top of the filter. Most Hayward filters have four to six bolts around the perimeter of the lid. Use your wrench to loosen them in a criss-cross pattern (like removing a car wheel) so the pressure comes off evenly. Lift the lid straight up and set it aside on a clean surface.

Now remove the old sand. If you have a wet/dry vacuum, use it to suck out the sand—this is the fastest method. If you are scooping by hand, use a bucket and work carefully to avoid damaging the internal parts. The sand will be heavy and wet, so take your time. Once most of the sand is out, use the garden hose to rinse the inside of the tank and wash away any remaining sand dust.

Cleaning the filter's internal parts

Inside the tank you will see the filter's internal assembly—usually a central pipe with lateral arms at the bottom that distribute water. Rinse this assembly thoroughly with the garden hose to remove any sand or debris stuck to it. Pay special attention to the lateral arms and any small openings; sand particles left behind can cause problems when you refill.

Check the lateral arms for cracks or damage. If you see cracks, the laterals need to be replaced before you add new sand—sand will escape through the cracks and clog your pool pump. Hayward sells lateral replacement kits for most models. If the laterals look intact, continue with refilling.

Adding the new sand in the correct layers

Hayward filters use three layers: gravel at the bottom, sand in the middle, and smaller gravel at the top. This layering helps water flow evenly and prevents sand from escaping. Start by adding the bottom layer of gravel—usually about 25 to 30 pounds depending on your filter size. Pour it slowly into the tank and spread it evenly across the bottom.

Next, add the sand. Pour it slowly into the tank while gently running water from the hose into the tank at the same time. This keeps the sand from compacting too much and helps it settle evenly. Fill the sand to the level specified in your filter's manual—usually about two-thirds of the way up the tank. Once the sand is in, add the top layer of smaller gravel, usually about 10 to 15 pounds.

Do not overfill. If sand reaches too high, it can escape into the pool when the filter runs. If you are unsure about the exact amount, it is better to add slightly less sand than too much.

Reassembling the filter and running the backwash cycle

Place the filter lid back on top of the tank, making sure it sits flat and even. Bolt it down in a criss-cross pattern, tightening each bolt a little at a time so the pressure is even. Do not over-tighten—you only need them snug enough that the tank does not leak.

Close the drain plug at the bottom of the tank. Open the filter's air relief valve (a small valve on top of the lid) and begin filling the tank with water from the hose. Watch the air relief valve; when water starts to come out of it, close the valve. This removes air pockets from the sand.

Turn the pump back on and set the filter valve to Backwash mode. Run it in backwash for three to five minutes. You will see dirty water flow out of the backwash line. This settles the sand and removes any remaining dust. Once the water runs clear, turn off the pump, switch the valve back to Filter mode, and turn the pump back on. Your filter is now ready to use.

Signs that sand replacement is overdue

If your pool water stays cloudy even after running the filter for several hours, or if the filter pressure gauge reads higher than normal (usually above 20 PSI), the sand may be clogged. Backwashing should bring the pressure back down temporarily, but if it climbs again within a few days, replacement is likely needed soon.

Another sign is reduced water flow—if water is moving slowly through the return jets, the sand is probably too clogged to let water pass. If you have not replaced the sand in more than three years, replacement is a good preventive step even if the filter seems to be working.

Frequently Asked Questions

Can I use regular play sand or construction sand instead of pool-grade sand?

No. Play sand and construction sand contain clay and other materials that break down in water and clog the filter faster than pool-grade sand. Pool-grade silica sand is specifically processed to resist breakdown and is worth the small extra cost.

What happens if I do not rinse the internal parts before adding new sand?

Old sand dust left inside can mix with the new sand and reduce the filter's effectiveness. It also can cause uneven water flow through the sand layers. Rinsing takes only a few minutes and makes a real difference in how well the filter works afterward.

How do I know if my filter's lateral arms are cracked?

Look for visible cracks or splits in the plastic or fiberglass arms at the bottom of the internal assembly. If you see cracks, sand will escape into the pool and clog the pump. Laterals are not expensive to replace and should be done before you add new sand.

Do I need to turn off the pump before opening the filter tank?

Yes, always. The tank is under pressure when the pump is running, and opening it while pressurized can cause water to spray out suddenly and damage the filter or injure you. Turn off the pump and let the system sit for a few minutes before opening any valves or bolts.

How often should I replace the sand?

Most pool owners replace sand every one to three years depending on pool use and how often they backwash. If you backwash regularly and keep the filter clean, sand lasts longer. If you notice the filter is not working well or pressure stays high even after backwashing, it is time to replace it.