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How to change pool filter sand

Updated: 16.10.2026

The water has gone dull and the 16/30 bags are ready. This is how to change pool filter sand: isolate the pump, empty the tank without breaking laterals, pour new sand onto water, then backwash and rinse. The grade belongs on the [pool filter sand buying guide](/hub/pool-care/filter-sand/sub/filter-sand-buying-guide). The [filter sand comparison](/hub/pool-care/filter-sand) is fibre balls, and one Windspeed review says not to backwash them. The Products Compared editorial team compiled these steps on 15 October 2026 from Pool and Spa Centre, Automated Environmental Systems, Bestway and HSE’s dust note. We did not open a tank. A qualifying purchase through our links can earn a commission at no extra cost to you.

The water has gone dull and the 16/30 bags are ready. This is how to change pool filter sand: isolate the pump, empty the tank without breaking laterals, pour new sand onto water, then backwash and rinse.

Our top picks

Windspeed Windspeed 1,400 g pool filter balls

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Windspeed Windspeed 1,400 g pool filter balls
6.5/10about £11.99
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Intex Intex 29045 fibre balls, 500 g

Rank 2

Intex Intex 29045 fibre balls, 500 g
7.4/10about £10.99
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Rakiuty Rakiuty 200 g pool filter balls

Best value

Rakiuty Rakiuty 200 g pool filter balls
5.5/10about £3.99
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On this page
  1. 1.Before you open the tank
  2. 2.Getting the old sand out
  3. 3.Pouring the new sand
  4. 4.The first backwash and rinse
  5. 5.When to stop

Before you open the tank

Switch the pump off and isolate it before you touch the valve or the lid. Automated Environmental Systems and Bestway both put the pump off before the handle moves, and Bestway says not to move the valve while the pump is running. Confirm the sacks print 16/30 in a band your manual allows. Intex says play sand and beach sand can spoil the filter and void the warranty. The label weight is the amount you stop at. The Intex SX925 listing asks for 6.5 kg, so emptying every sack is how a small tank gets buried. Fibre balls leave this procedure for the filter balls versus sand page.

Getting the old sand out

Pool and Spa Centre describes two routes. Use the drain plug when the tank has one. When it has none, they describe a plastic cup, because a shovel is what cracks a lateral or the wall. The pump stays off. Let the tank drain before you reach inside. Look at the laterals once you can see them. A broken finger sends sand back to the pool however careful the new fill is.
Windspeed Windspeed 1,400 g pool filter balls

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Windspeed Windspeed 1,400 g pool filter balls
6.5/10about £11.99
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Pouring the new sand

Cover the laterals with water first. Pool and Spa Centre says the tank should be about half full before the new sand goes in. Dry silica dropped onto bare laterals is how those pipes get smashed. Stop at the label weight, or between the level marks if that is what the manual prints. Bestway wants the sand between the marks, at about 0.45–0.85 mm. A full 25 kg bag in a tank that asks for 6.5 kg, as on the SX925 listing, would bury the laterals. Reassemble the tank the way the manual shows, with the pump still off, and move the valve to backwash before anyone starts the motor.

The first backwash and rinse

Turn the handle to backwash while the pump is off, start the pump only after the valve is seated, and run to waste until the water is clear. Automated Environmental Systems, writing a routine backwash rather than a full media change, says that can take about three to five minutes, then a rinse of about ten seconds, then filter. Bestway’s new-fill instruction is the same order without those minutes: backwash, rinse, and leave the valve alone while the pump runs. Switch the pump off before each handle move. Sand that keeps returning after the grade and the level are right points at a damaged lateral.

When to stop

Stop if a lateral is cracked, if the kilogram label is missing, or if you cannot isolate the pump on an in-ground tank. Stop if the pool is a public, school or club bath. Stop as well if the sacks are fibre balls. Those are washed out of the tank, and this backwash sequence is the sand job. The best pool filter sand page is where the bag choice belongs, before the lid is off. When the bags, the laterals and the label agree, finish on filter only after the waste has run clear and the rinse has had its turn.

Common questions

How do I get the old sand out?
Isolate the pump first. If the tank has a drain plug, Pool and Spa Centre uses that. If it does not, they describe a plastic cup rather than a shovel, so the laterals and the wall stay intact. Drain the water before you reach inside, and look at the laterals once you can see them. A cracked finger is a reason to stop. New sand goes in only after that look.
Should the tank be wet before I pour?
Cover the laterals before the silica goes in. Pool and Spa Centre describes the tank as about half full at that point. Dry sand dropped onto bare laterals is a common way to break them, and a broken lateral returns sand to the pool. Pour without a dust cloud. HSE’s eight-hour workplace limit is not a measurement of your bag.
How full do I fill it?
Stop at the kilograms on the tank label, or between the level marks, which is Bestway’s instruction. A 25 kg bag is a shop unit. The SX925 listing’s 6.5 kg of silica is less than one bag. Filling above the mark leaves the bed no room to lift on backwash, which is one route to sand in the pool.
What valve position comes first?
Backwash comes first, and the pump is off while you move the handle. Run to waste until the water is clear. AES’s routine-backwash guide says about three to five minutes, then about ten seconds of rinse, then filter, with the pump off at each turn. Those minutes are theirs, for a routine backwash. Bestway asks for the same first backwash and rinse, and says not to move the valve while the pump runs.
Why is sand in the pool after a new fill?
Bestway’s page points at the grain, the level and the valve. Sand comes back when the grain is outside about 0.45–0.85 mm, the bed sits above the marks, the valve was turned while the pump was running, or the first backwash and rinse were skipped. Sand that continues after the grade and the level are right points at a damaged lateral. Dull water can also be a chemistry problem.
Can I use the same steps for filter balls?
Fibre balls are removed and washed. UK reviews describe a machine wash, one of them with no fabric conditioner, and a Windspeed review says not to use the backwash setting. The drain plug, the half-full tank and backwash-until-clear are the silica sequence. If you bought the packs on the main comparison, use the balls-versus-sand page instead of this valve order.

Related pages

Glass filter media versus sand

Filter sand

Best pool filter sand for a UK domestic sand filter

Pool filter sand: the 16/30 grade and the 25 kg bags

Filter balls vs sand: backwash the bed or wash them

Sources

Public UK sources and amazon.co.uk listings used for this comparison, checked on 15 October 2026.

  1. PWTAG Technical Note 50: swimming pool filter specification (retrieved 15.10.2026)
  2. PWTAG filtration rate calculator (retrieved 15.10.2026)
  3. Holcim UK swimming pool filter sand (retrieved 15.10.2026)
  4. PoolStore filter sand 16/30, 25 kg bag (retrieved 15.10.2026)
  5. h2ofun swimming pool sand filter media, 25 kg (retrieved 15.10.2026)
  6. Intex: play sand and beach sand in a sand-filter pump (retrieved 15.10.2026)
  7. HSE INDG463: control of exposure to silica dust (retrieved 15.10.2026)
  8. Poolpro fibre-ball media for Intex sand-filter pumps, 500 g (retrieved 15.10.2026)