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Gear

Filter Media & Cartridges

Media is where a filter stops being a pump and starts being a filter. It is also where the largest self-inflicted injury in the hobby happens: replacing everything at once because the packaging says monthly, and taking the bacterial colony out with the carbon. The rule that runs through this whole category is to stagger. Change one piece, leave the other, and give the colony somewhere to be while the new material settles in.

Core job: what actually does the filtering, and when it gets replaced · 9 products listed

Read this first

  • Rinse media in a bucket of water you have just taken out of the tank. Municipal tap water is disinfected specifically to kill bacteria and it does not spare yours.
  • Never replace all media in one session. In a single-cartridge filter, run the new piece alongside the old one for two to four weeks before removing the old one.
  • Chemical media exhausts. Once carbon or a resin is spent it occupies space and does nothing — but it is not doing harm either, so there is no need to rush a change while the tank is unsettled.
  • Media that adsorbs ammonium removes the food supply your nitrifying bacteria are trying to grow on, which can lengthen a cycle. Use it deliberately, not by default.

What actually separates one from another

  • Whether the filter housing takes more than one piece at a time. If it does not, you can often run a piece of foam alongside a cartridge for a few weeks before swapping it.
  • What the medium is actually for. Floss and foam strain particles, ceramic and sponge house bacteria, carbon and resin bind dissolved material — and the replacement schedule differs for each.
  • Fit. Cartridges are model-specific and the packaging lists which filters they suit; cut-to-size foam is the flexible answer when nothing fits.
  • The replacement interval the manufacturer prints, which is about the chemical component. The biological component is not on a schedule and should be left alone.

Side by side

Cartridges — 7 products
ProductKey specBest for
Tetra Whisper Bio-Bag Cartridges, Large, 3-pack3-pack, large, wide fit listWhisper, PF and IQ filters in the size range the listing specifies.
PF-S Filter Cartridges, 15-pack15-pack, carbon with zeoliteA Silenstream PF10 owner who would rather order once than four times a year.
Aqueon Replacement Cartridges, Medium, 3-pack3-pack, medium, QuietFlow 10QuietFlow size 10 filters where the stock cartridge is the media.
Aqueon Replacement Cartridges, Large, 3-pack3-pack, large, canister 200-400Canister filters in the 200 to 400 range the listing names.
Tetra Whisper Bio-Bag Cartridges, Medium, 3-pack3-pack, medium, monthlySmall Whisper, PF-10 and IQ 10 filters on tanks in the 5 to 10 gallon range.
Marineland Penguin Bio-Wheel Cartridges, Rite-Size C, 6-pack6-pack, Rite-Size CPenguin Bio-Wheel filters taking the Rite-Size C cartridge.
Tetra ReptoFilter Cartridges, 3-pack3-pack, four-week intervalReptoFilter 20 gallon and Viquarium habitats.
Foam and chemical media — 2 products
ProductKey specBest for
Aquarium Sponge Filter Pad, 20 x 20 x 1 in20 PPI foam, 20 x 20 x 1 inAny filter, and specifically any single-cartridge filter that needs a second piece of media.
Seachem Purigen, 100 ml100 ml organic resinClearing dissolved organics and yellow tint in a tank that is otherwise well maintained.

The products

Cartridges

Model-specific consumables that combine mechanical and chemical media in one frame. Check the compatibility list on the pack, and stagger replacements.

  • Tetra Whisper Bio-Bag Cartridges, Large, 3-pack

    Core pick

    Tetra Whisper Bio-Bag Cartridges, Large, 3-pack

    3-pack, large, wide fit list

    A three-pack of large Bio-Bag cartridges with the widest stated compatibility list in this category. If your filter is on that list, this is the straightforward replacement. Add a new cartridge alongside the old one rather than swapping outright, so the bacterial colony has somewhere to stay.

    Why this badgeIts stated fit list is the widest here — Whisper 10-30 and 20-40 gal, PF-20 to 60, and IQ 20 to 60.

    The listing states these fit Whisper 10-30 and 20-40 gallon filters, PF-20 to PF-60, and IQ 20 to IQ 60.

    Good

    • The broadest stated fit list here, covering several Whisper, PF and IQ models.
    • Three per pack, which covers a quarter of a year on a monthly interval.
    • Drop-in fit means no cutting or trimming.
    • Combines mechanical floss and chemical media in one frame.

    Watch out

    • A cartridge design encourages replacing the whole thing, and the whole thing includes your bacteria.
    • Model-specific, so it is useless if your filter is not on the list.
    • The chemical component is spent well before the frame stops straining water, so the interval is set by the part you cannot see.

    Best forWhisper, PF and IQ filters in the size range the listing specifies.

    Check it on Amazon
  • PF-S Filter Cartridges, 15-pack

    Longest run between orders

    PF-S Filter Cartridges, 15-pack

    15-pack, carbon with zeolite

    A fifteen-cartridge pack containing carbon with zeolite, listed as compatible with Silenstream PF10. The pack size means a very long interval between orders. The zeolite content is worth understanding before you commit to it, because it adsorbs ammonium and that has consequences during a cycle.

    Why this badgeFifteen cartridges per pack, the largest count in this category.

    The listing states these contain carbon with zeolite and are compatible with Silenstream PF10.

    Good

    • Fifteen per pack is by far the largest count here and covers more than a year on a monthly interval.
    • Carbon and zeolite together cover two different chemical filtration jobs.
    • Compatibility is stated explicitly for the Silenstream PF10.
    • Buying in one large pack means never being caught without a spare.

    Watch out

    • Zeolite removes ammonium, which is the food supply the nitrifying bacteria are trying to grow on — that can lengthen a cycle.
    • Fifteen cartridges is a long time for the last ones in the pack to sit in storage.
    • Compatibility is stated for one filter, so it does not travel to a different setup.

    Best forA Silenstream PF10 owner who would rather order once than four times a year.

    Check it on Amazon
  • Aqueon Replacement Cartridges, Medium, 3-pack

    Aqueon Replacement Cartridges, Medium, 3-pack

    3-pack, medium, QuietFlow 10

    A three-pack of medium cartridges built from dual-sided dense floss with activated carbon, listed for QuietFlow size 10 filters. The dense floss is the mechanical half and the carbon is the chemical half, which is why the replacement interval is set by the carbon. Stagger the change rather than swapping outright.

    The listing states these are dual-sided dense floss with activated carbon, for QuietFlow size 10.

    Good

    • Dual-sided dense floss gives more mechanical surface than a single-face pad.
    • Three per pack covers a quarter on a monthly interval.
    • Compatibility is stated explicitly for QuietFlow size 10.
    • Combines mechanical and chemical filtration without needing separate bags.

    Watch out

    • Dense floss clogs faster than coarse foam and needs rinsing between changes to hold flow.
    • Model-specific fit limits it to one filter family.
    • Replacing the cartridge removes the colony living on it, which is why a second piece of media matters.

    Best forQuietFlow size 10 filters where the stock cartridge is the media.

    Check it on Amazon
  • Aqueon Replacement Cartridges, Large, 3-pack

    Aqueon Replacement Cartridges, Large, 3-pack

    3-pack, large, canister 200-400

    Large cartridges with activated carbon and a rinse-and-install tab, listed for canister filter models 200 to 400. The tab is a small convenience that matters more than it sounds, because it makes the pre-install rinse something you actually do. Three per pack.

    The listing states these contain activated carbon, have a rinse-and-install tab, and suit canister filter 200-400.

    Good

    • The rinse-and-install tab makes handling straightforward without touching the media face.
    • Activated carbon covers the dissolved-organics job that foam cannot.
    • Three per pack matches a quarterly ordering habit.
    • Stated compatibility with canister models 200 to 400 removes the guesswork.

    Watch out

    • Canister-specific, so it does not fit hang-on-back or internal units.
    • The carbon is spent long before the cartridge looks used up.
    • Replacing all cartridges in a canister at once is a genuine risk to the colony in that filter.

    Best forCanister filters in the 200 to 400 range the listing names.

    Check it on Amazon
  • Tetra Whisper Bio-Bag Cartridges, Medium, 3-pack

    Tetra Whisper Bio-Bag Cartridges, Medium, 3-pack

    3-pack, medium, monthly

    The medium size of the same Bio-Bag family, listed for Whisper 5 to 10 gallon filters, PF-10 and IQ 10, with a stated monthly replacement interval. On a small filter with only one cartridge slot, adding a piece of cut foam alongside it is what makes that monthly change safe.

    The listing states these fit Whisper 5-10 gallon filters, PF-10 and IQ 10, with monthly replacement.

    Good

    • Correct size for the small Whisper, PF-10 and IQ 10 filters the listing names.
    • The monthly interval is stated on the listing rather than left to guesswork.
    • Three per pack suits a small tank that gets through media slowly.
    • Drop-in fit with no trimming.

    Watch out

    • Small filters often hold one cartridge only, so a straight monthly swap takes the whole colony with it.
    • Restricted to the small models named on the listing.
    • A medium cartridge holds less media than the large version of the same product.

    Best forSmall Whisper, PF-10 and IQ 10 filters on tanks in the 5 to 10 gallon range.

    Check it on Amazon
  • Marineland Penguin Bio-Wheel Cartridges, Rite-Size C, 6-pack

    Marineland Penguin Bio-Wheel Cartridges, Rite-Size C, 6-pack

    6-pack, Rite-Size C

    A six-pack of Rite-Size C cartridges for Penguin Bio-Wheel filters. The Bio-Wheel design keeps a substantial part of the biological colony outside the cartridge, which makes cartridge changes on these filters less disruptive than on most — provided you leave the wheel itself alone.

    The listing states these are replacement cartridges for Penguin Bio-Wheel filters, supplied as a 6-pack.

    Good

    • Six per pack, twice the count of most three-packs here.
    • Designed for a filter family where the bio-wheel carries colony independently of the cartridge.
    • Straightforward drop-in replacement with no trimming.
    • A long ordering interval for a filter in regular use.

    Watch out

    • Only fits Penguin Bio-Wheel filters that take the Rite-Size C format.
    • The bio-wheel itself must never be scrubbed or replaced casually, and that is easy to forget during a cartridge change.
    • Six cartridges means the last ones sit in storage for a long time.

    Best forPenguin Bio-Wheel filters taking the Rite-Size C cartridge.

    Check it on Amazon
  • Tetra ReptoFilter Cartridges, 3-pack

    Tetra ReptoFilter Cartridges, 3-pack

    3-pack, four-week interval

    A three-pack of cartridges for the ReptoFilter 20 gallon and Viquarium, with a stated four-week replacement interval. These are for reptile and turtle habitats rather than fish tanks, which is worth knowing before you match them to a filter by size alone.

    The listing states these fit the ReptoFilter 20 gallon and the Viquarium, with replacement every four weeks.

    Good

    • Stated fit for two specific units, so compatibility is unambiguous.
    • The four-week interval is printed on the listing rather than implied.
    • Three per pack matches a quarterly ordering habit.
    • Built for the heavier waste load a reptile habitat produces.

    Watch out

    • Intended for reptile and turtle setups rather than for a fish aquarium.
    • Fits only the two units named on the listing.
    • A four-week cycle on a single-cartridge filter needs a second piece of media alongside it to be safe.

    Best forReptoFilter 20 gallon and Viquarium habitats.

    Check it on Amazon

Foam and chemical media

Loose media you fit to the filter rather than the other way round. Foam is mechanical and biological at once; resins and carbon are chemical and have a working life.

  • Aquarium Sponge Filter Pad, 20 x 20 x 1 in

    Most adaptable

    Aquarium Sponge Filter Pad, 20 x 20 x 1 in

    20 PPI foam, 20 x 20 x 1 in

    A large sheet of 20 PPI foam you cut to fit whatever housing you have. This is the answer when nothing off the shelf fits, and it is also the piece of media most worth adding to a single-cartridge filter so the colony has somewhere permanent to live. Foam is rinsed and reused rather than thrown away.

    Why this badgeA 20 x 20 x 1 in sheet cut to size fits any housing, unlike every fixed-shape cartridge here.

    The listing states this is 20 PPI foam, supplied as a 20 x 20 x 1 inch sheet, cut to size.

    Good

    • Cuts to fit any filter, which makes it useful across every model in this list and any future one.
    • A single 20 x 20 inch sheet yields a great many pieces.
    • Foam holds a bacterial colony well and is designed to be rinsed and reused indefinitely.
    • Gives a single-cartridge filter a second piece of media, which is what makes staggered replacement possible.

    Watch out

    • Requires cutting and fitting rather than dropping straight in.
    • 20 PPI is a coarse-to-medium grade, so it will not polish water the way fine floss does.
    • It contains no chemical media, so it does nothing about tannins or dissolved organics.

    Best forAny filter, and specifically any single-cartridge filter that needs a second piece of media.

    Check it on Amazon
  • Seachem Purigen, 100 ml

    Seachem Purigen, 100 ml

    100 ml organic resin

    A 100 ml quantity of synthetic organic filtration resin. This is chemical media rather than a cartridge — it goes into the filter in a bag and targets dissolved organic compounds. It is the reason this product belongs in filter media and not, as it is sometimes miscategorized, among test kits.

    The listing states this is a synthetic organic filtration resin.

    Good

    • Targets dissolved organics, which is the class of material responsible for yellowing water.
    • A resin is finer in its action than activated carbon on the same job.
    • Runs in a mesh bag, so it fits any filter with room for one.
    • 100 ml is a workable quantity for a typical home tank.

    Watch out

    • Chemical media exhausts and needs attention on the manufacturer's schedule.
    • It does not remove nitrate, and people frequently expect it to.
    • It needs a mesh bag, which may not be supplied with the filter you own.

    Best forClearing dissolved organics and yellow tint in a tank that is otherwise well maintained.

    Check it on Amazon

Common questions

My cartridge says replace monthly. Should I?

The monthly figure is about the carbon inside it, which is genuinely spent by then. The frame and floss are also carrying your bacterial colony, so the answer is to replace on that interval but never all at once — add the new cartridge alongside the old one and remove the old one two to four weeks later.

Can I just rinse a cartridge instead of replacing it?

You can rinse it in tank water to restore flow, and that is worth doing weekly. What rinsing cannot do is regenerate the activated carbon inside, so if you are relying on the chemical part it still needs replacing on schedule.

What is the difference between foam and a cartridge?

A cartridge is a fixed-shape consumable built for one filter model, usually combining floss and carbon. Foam is a sheet or block you cut to fit, it holds bacteria very well, and it is designed to be rinsed and reused rather than thrown away. Many people end up running both.

Does any of this remove nitrate?

Not in useful quantities. Activated carbon and organic resins target dissolved organics, not nitrate. Nitrate comes down through water changes and plant growth, and nothing you put in a filter substitutes for that.

Where this comes up

Parameters this category touches