The Aqua One AquaStyle 850 takes the Aqua One Sponge 4s (25004S) for AquaStyle 850 as its filter media; Australian sellers list it from A$10.44 each as of 29 October 2026. Fitment confirmed against the manufacturer's compatibility list.
Your aquarium filter
Aqua One AquaStyle 850
Aquarium filter
Confirmed against Aqua One's listConfirmed against Aqua One's own compatibility list
Not yours? Change
Takes the 25004S filter media
Sponge 4s (25004S) for AquaStyle 850 · check the code printed on your old filter before ordering.
Your aquarium filter
Aquarium filter
Confirmed against Aqua One's listConfirmed against Aqua One's own compatibility list
Takes the 25004S
Filter media · check the code on your old filter.
Other Aqua One aquarium filters and their replacement media
The 25004S fits the AquaStyle 850 only. These Aqua One models take a different filter media:
GenuineGenuine Aqua One
$10.44 each
2-pack $20.88
Aquarium Spare Parts · 29 OctLowest genuine · Aquarium Spare Parts · checked 29 Oct
CompatibleCompatible option
See seller
No compatible seller tracked yetNo compatible seller tracked yet
Genuine: made by Aqua One. Compatible: another brand.Genuine is made by Aqua One. Compatible is made by another brand. Check the seller's page for the size and models it fits.
Lowest price · $10.44 each · 2-pack $20.88
Aquarium Spare Parts. Every seller we track is listed below. Some links earn us a commission. Some seller links earn us a commission, at no extra cost to you.
Other parts this aquarium filter takes
- Aqua One Carbon Cartridge 4c (25004C) for AquaStyle 850Open Aquarium Spare Parts$13.94 each · 2-pack $27.88
The carbon filter. Separate from the filter media. Reduces dissolved waste, odours and discolouration (activated carbon). Replace every 2 months.
- Aqua One Wool 4w (25004W) for AquaStyle 850Open Aquarium Spare Parts$6.94 each · 2-pack $13.88
The fine pad. Separate from the filter media. Reduces micro-particles (fine wool, mechanical).
Compare 1 seller
AUD, before delivery. Each price shows when it was checked.
Opens Aquarium Spare Parts in a new tab. Their page is the source of truth for price, delivery and returns.
How long it lasts
Replace it when it clogs, breaks down or no longer holds its shape, Aqua One says; until then rinse it in a bucket of aquarium water each time you clean the filter.
How to change the filter media in your Aqua One AquaStyle 850
Watch the guide or follow the steps.
No clear video for this part yet. The steps cover it.
- 1Turn the power head off and unplug the aquarium's equipment.
- 2Remove the lid from the filter unit and lift the elbow and spray bar off the top of the power head.
- 3Take out the carbon cartridge and the black filter sponge. Rinse the sponge in a little aquarium water in a bucket, then throw that water away rather than adding it back to the tank.
- 4Put the sponge back, or fit a new one once the old one blocks up or breaks down.
- 5Refit the spray bar with its holes pointing down onto the carbon cartridge, make sure the tank is full, turn the power head on and check that water flows from the spray bar. Close the lid.
Every number this part goes by
- Retail name:
- 25004S
- Retail name:
- 4S
Sellers list any of these; they are the same part.
About your Aqua One AquaStyle 850
Aqua One aquarium filter — AquaStyle aquarium. Its filter media is the Sponge 4s (25004S) for AquaStyle 850, part 25004S.
Also in this aquarium filter: Aqua One Carbon Cartridge 4c (25004C) for AquaStyle 850 (every 2 months), Aqua One Wool 4w (25004W) for AquaStyle 850.
Where the model number is: The model is on the filter's lid, motor head or a label on its side (Fluval 307, Eheim Classic 2215). For a tank with a built-in filter, use the tank's name.
Fits this Aqua One model
Aqua One1 model
Common questions
- Which filter media fits the Aqua One AquaStyle 850?
- The Aqua One AquaStyle 850 takes the Aqua One Sponge 4s (25004S) for AquaStyle 850.
- Where can I buy the 25004S in Australia?
- We track 1 Australian seller for the 25004S; the lowest listed price when we last checked was A$10.44 at Aquarium Spare Parts. Prices are re-checked daily and dated on this page.
- How do I fit the 25004S in an Aqua One AquaStyle 850?
- No tools, a few minutes: 5 steps, listed on this page with the replacement video where the maker has one.
- What happens if I don't change it?
- Spent carbon stops removing odours and discolouration, and clogged pads slow the flow, so the filter moves less water through the tank.
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