Pool filter sand should be changed every 5 to 7 years. Over time, the grains wear smooth, develop channels (water finds a path of least resistance and stops contacting the filter media), and lose their ability to trap fine particles. Backwashing won’t fix it — once channels form, the sand needs to be physically replaced. Here’s the full step-by-step from old sand out to new sand in.
When to change sand (not just backwash)
- Filter pressure won’t drop to clean baseline after a thorough backwash.
- You’re backwashing more frequently with shorter clean cycles.
- Water looks slightly cloudy even with normal pressure.
- It’s been more than 5–7 years since the last change.
What you’ll need
- The right sand for your filter — #20-grade silica pool filter sand OR zeolite if your filter is sized for it
- The correct sand quantity for your filter (most residential filters take 100–300 lb; check your filter’s label)
- A wet/dry shop vacuum
- A bucket or large bowl to cover the standpipe
- Duct tape
- A new tank o-ring or band-clamp gasket
- Silicone pool lubricant
- A new pressure gauge if yours is foggy or stuck
Step-by-step: changing pool sand
Shut off the pump at the breaker. Open the air-relief valve on top of the filter and let pressure bleed to zero.
Open the drain plug at the bottom of the filter and let all water drain out. This takes 15–30 minutes for a typical residential filter.
Unscrew the two PVC unions on either side of the multiport valve and lift it free. On top-mount filters the valve sits on a standpipe; lift it carefully so you don’t snap the pipe. On side-mount filters, disconnect the plumbing and set the valve aside.
Cover the top of the standpipe with a plastic cup or bowl, taped on with duct tape, so no sand falls into the standpipe and down to the laterals. Sand in the standpipe means sand returning to your pool every time the pump runs.
Use a small plastic cup or wet/dry shop vac to remove the wet sand. Take it out a few cups at a time. This is the slow part — budget 30–45 minutes. Don’t shovel aggressively near the bottom — the laterals at the base of the standpipe are thin plastic and break easily.
With the sand removed, look at the laterals (the radial fingers at the bottom). Look for cracks, missing tips, or worn slots. Replace any that look damaged before you put new sand in — they’re cheap, and changing them now saves you opening the filter again next year.
Add water to the filter housing through the open standpipe until it’s about a third full. The water cushions the laterals when you pour sand in.
With the standpipe still covered, pour fresh #20-grade pool filter sand around the standpipe until you hit the “sand level” line marked inside the filter (or until the sand is about 2/3 the way up the housing). Pour slowly and evenly to avoid damaging the laterals.
Always replace the o-ring — never reuse the old one. Lubricate with silicone, set in the groove, reinstall the multiport, and hand-tighten the unions plus a quarter turn with channel-locks.
New sand has fine dust that will cloud your pool if you don’t flush it first. Set the multiport to BACKWASH, run for 3–5 minutes, then to RINSE for another minute. Then switch to FILTER and check for leaks.
What sand to buy
Use only certified pool filter sand — either #20 silica sand or pool-grade zeolite. Play sand, mason sand, and beach sand are all wrong grain size and will pass through the laterals or pack down. Most local hardware stores and pool centers carry the 50 lb bags. Quantity needed varies by filter size (your filter label will tell you).
Replace these small parts at the same time
While the filter is open is the only time you’ll see these parts for the next 5+ years. Replace them now:
Pump Strainer Top Lid Gasket
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Hayward Pump Strainer Basket
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Taylor K-2006 Test Kit
Shop NowAfter the change
Run the filter for 24 hours. Check pressure — it should be lower than before. Retest pool chemistry the next day; new sand sometimes shifts pH slightly. If your pool returns sand to the pool after the change, the cause is almost always a broken lateral that wasn’t replaced — reach out to PST and we’ll match the right lateral set for your filter model.