Filters

How to Change the Sand in a Pool Filter

A two-hour job every few years. Here are the steps, the sand amounts and the mistakes to avoid.

Updated November 2026

Short answer

Change filter sand about every 3 to 5 years, or sooner if the water stays cloudy and pressure climbs quickly after each backwash. Use #20 silica pool filter sand and the amount printed on the tank label.

The job takes about two hours. The one rule that prevents damage: put water in the tank before you pour in the new sand.

Pool filter guide

Not sure the sand is the problem? The guide covers pressure readings and cloudy water.

How much sand does my filter take?

Typical pounds of sand by sand filter tank diameter
Tank diameter	Typical sand load	50 lb bags
16 inch	100 lbs	2
18 to 19 inch	150 lbs	3
21 inch	200 lbs	4
22 to 23 inch	250 lbs	5
24 inch	300 lbs	6
27 inch	350 lbs	7
30 to 31 inch	500 lbs	10

These are typical figures. Tanks of the same width can differ, so use the amount on your tank label or in the manual.

How do I change the sand?

Turn off the pump at the breaker so it cannot start while the filter is open.
Release the pressure and drain the tank. With the pump off, open the air relief valve on top of the filter if it has one and wait for the gauge to read zero. Then remove the drain plug at the bottom and let the water run out.
Remove the valve or lid. Undo the clamp or collar and the pipe unions, then lift the valve straight up. Do not twist it, or you can snap the standpipe below.
Cover the standpipe opening with a cup or tape so no sand gets inside it.
Take out the old sand. Scoop it with a plastic cup or use a shop vacuum. Work gently near the bottom, where the laterals are.
Check the laterals. Rinse the tank and look at the slotted fingers at the base. Replace any that are cracked. A broken lateral sends sand into the pool.
Fill the tank halfway with water. The water cushions the laterals when the sand lands on them.
Pour in the new sand slowly, keeping the standpipe centered and covered.
Reassemble, with a light coat of o-ring lubricant on the valve o-ring so it seals. Then backwash for 2 to 3 minutes and rinse for 1 minute before returning to Filter. Turn the pump off every time before you move the valve handle, or you can damage the valve. This washes out dust.

Wet sand is heavy and dry sand makes dust. Lift with care and wear an N95 mask when pouring.

How do I know the sand needs changing?

The water stays dull or cloudy even though chemistry is in range.
Pressure climbs back up within a day or two of backwashing.
Backwashing takes longer than it used to, or the water never runs clear.
The sand feels greasy, clumps together or has hard channels in it.

If the sand is only a few years old, a deep clean with filter cleaner may be enough. Sand coming out of the return jets is a different problem: a cracked lateral or standpipe.

Frequently Asked Questions

Can I use play sand in a pool filter?

No. Play sand is too fine and uneven. It clogs, passes into the pool and can damage the system. Use #20 silica sand sold as pool filter sand.

Can I use filter glass or other media instead of sand?

Yes, if your filter maker allows it. Glass media and similar products filter finer than sand and usually need less weight. Follow the amount on the product for your tank size.

Why is sand coming into my pool after I changed it?

A little dust in the first minutes is normal. Sand that keeps coming means a broken lateral, a cracked standpipe or sand that got inside the standpipe during the refill.

Do I need to fill the tank all the way to the top with sand?

No. The correct load leaves open space at the top so the sand can lift and rinse during a backwash. How much space depends on the tank. On some tanks the sand comes to within 6 inches of the top, so go by the weight on the label, not by how full it looks.

Sources

Get more out of your filter

Pressure readings, backwash timing, deep cleaning and how the multiport valve works.

Pool Filter Guide How Pool Valves Work