Independent comparisons. We may earn from shop links. More info

Pool filter sand: the grade and the bag count

Updated: 16.10.2026

You already own the sand filter, and the next purchase is the media inside it. Search for pool filter sand on amazon.co.uk and you get fibre-ball packs rather than graded silica. By the end you should know the grade to ask a UK pool shop for, how the kilograms on the tank become 25 kg bags, and which listings are a different object. The six ball packs, from £3.99 to £13.99, are on the [filter sand comparison](/hub/pool-care/filter-sand). The Products Compared editorial team checked UK shop pages, PWTAG’s filter note and those amazon.co.uk files on 15 October 2026. We did not pour a bag. A qualifying purchase through our links can earn a commission at no extra cost to you.

You already own the sand filter, and the next purchase is the media inside it. Search for pool filter sand on amazon.co.uk and you get fibre-ball packs rather than graded silica.

Our top picks

Windspeed Windspeed 1,400 g pool filter balls

Best overall

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

Rank 2

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

Best value

Rakiuty Rakiuty 200 g pool filter balls
5.5/10about £3.99
View offer
On this page
  1. 1.What pool filter sand is
  2. 2.How many 25 kg bags
  3. 3.What not to pour in
  4. 4.When the public-pool rules matter

What pool filter sand is

Pool filter sand, as UK pool shops use the words, is dried silica sold as grade 16/30. PWTAG Technical Note 50 specifies that grade, to BS EN 12904, for the sand filters the note covers, and names glass as the other common media. The millimetre band is where the shops diverge. h2ofun and Pool Tech Services print 0.4–0.8 mm on bags they call 16/30. Holcim’s Garside page prints 16/30 at 0.5–1.0 mm, also to BS EN 12904. Bestway asks for about 0.45–0.85 mm. The sack in your hand and the manual on the pump decide which of those bands you are allowed to pour. On 15 October 2026 a 25 kg bag was £22.50 at Pool Tech Services, £22.95 at h2ofun, £24 at Automated Environmental Systems and £26 including VAT at PoolStore. No amazon.co.uk price for a 25 kg silica bag was in this set.

How many 25 kg bags

The fill weight on the filter is the figure that matters. A 25 kg sack is the shop unit. PoolStore’s published examples run from 50 kg, two bags, to 425 kg, 17 bags. The Intex Krystal Clear SX925 listing asks for 6.5 kg of silica, not included. One shop bag is more than that tank holds, and you stop at the label or between the level marks. All Swim notes extra carriage and free collection in Cardiff.
Windspeed Windspeed 1,400 g pool filter balls

Testsieger

Windspeed Windspeed 1,400 g pool filter balls
6.5/10about £11.99
View offer

What not to pour in

Intex’s support page says play sand and beach sand can spoil the filter and void the warranty. Builders’ sand is not sold as 16/30 filtration silica, and PoolStore warns that grains which are too fine can come back through the laterals. Fibre balls are the miss an amazon.co.uk search is likely to produce. Rakiuty at £3.99 claims that 200 g replaces 4 kg of sand. yunwailc at £8.99 claims that 200 g replaces 5 kg, while its dimensions line says 190 g. Both sentences are seller claims, and they disagree. A deliberate switch belongs on the filter balls versus sand page. Glass stays in the tank and is backwashed, on the glass filter media versus sand page. HSE guidance INDG463 gives a workplace exposure limit of 0.1 mg/m³ for respirable crystalline silica over eight hours, and that figure is not a reading from one domestic bag. The order of emptying and refilling is on the how to change pool filter sand page.

When the public-pool rules matter

PWTAG’s filtration-rate page puts medium-rate filtration at 10–25 metres per hour for busy public pools, and high-rate at 25–50 metres per hour, which it describes as less effective. Many domestic filters sit in that high-rate band. An 800 mm public bed is not the fill line on a garden tank. The household filter follows its own label. A public bath, a school pool or a club pool is where this shopping list stops. Those tanks are an operator question. If sand returns after the grade and the level are already right, another sack repeats the symptom, and the tank needs someone who can open it. Buy the grade, the millimetres and the kilograms the manual prints, then stop the pour at the label.

Common questions

What grade do I buy for a normal pool sand filter?
For a domestic sand filter, UK shops and PWTAG Technical Note 50 point you to dried silica grade 16/30. Buy the kilograms on your tank, in a bag that prints that grade. On 15 October 2026 the 25 kg shelf prices we recorded ran from £22.50 at Pool Tech Services to £26 including VAT at PoolStore.
Is 16/30 the same as 0.4–0.8 mm?
Sometimes the bag says so, and sometimes it prints another band. h2ofun and Pool Tech Services print 0.4–0.8 mm on bags they call 16/30. Holcim prints 0.5–1.0 mm for 16/30 to BS EN 12904. Bestway asks for about 0.45–0.85 mm. Use the band your filter manual allows, and read the sack before you pay.
How many 25 kg bags does a domestic filter take?
Divide the fill weight by 25 kg, then stop the pour at the label rather than at the bottom of the last sack. PoolStore’s published examples run from 50 kg, two bags, to 425 kg, 17 bags. The Intex SX925 listing asks for 6.5 kg of silica, so one shop bag is more than that small pump holds. A 100 kg label needs four bags.
Can I use play sand or builders’ sand?
Intex says play sand and beach sand can spoil the sand filter and void the warranty. Builders’ sand is not 16/30 filtration silica, and grains that are too fine are what PoolStore warns can pass the laterals and return to the pool. Holcim’s 8/16 grade, at 1–2 mm, is coarser than the usual 16/30 bed. If the sack does not print the grade your manual names, leave it out of the tank.
Is a fibre-ball listing the same purchase?
A fibre-ball pack is a different object from a 25 kg sack of 16/30. In this comparison every kept amazon.co.uk listing is balls, from Rakiuty at £3.99, claiming to replace 4 kg of sand, through to larger packs with their own ratios. Those ratios are seller sentences, and they disagree. Buy balls only when you mean to switch and you know the grams your pump wants.
Does a public-pool bed depth apply to an above-ground tank?
A garden tank follows its own label. PWTAG’s medium-rate band of 10–25 metres per hour is written for busy public pools, and high-rate filtration at 25–50 metres per hour is where many domestic filters sit. An 800 mm public bed is not the fill line on an above-ground pump. School, club and public baths belong with the operator.

Related pages

Best pool filter sand

Filter sand

How to change pool filter sand: empty, pour, rinse

Filter balls vs sand: backwash the bed or wash them

Glass filter media versus sand: which bed to backwash

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)