Best Filter Media For A Healthier Aquarium

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Learning about aquarium filters can be a dizzying prospect, and that’s just hunting down the perfect piece of equipment for your tank! Once you’ve installed your system, though, you’ll run into the next challenge: identifying the best filter media to use inside it! Let’s explore these products and identify the ideal type for your tank!

Comparison Table Of The 6 Best Filter Media

tnk-table__imageFluval Pre-Filter Media
  • Type of Filtration: Medium to Coarse Mechanical
  • Material: Ceramic
  • Filter Style: Canister
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tnk-table__imageCNZ Aquarium Filter Media Kits
  • Type of Filtration: Chemical
  • Material: Compressed Carbon Cylinders
  • Filter Style: HOB/Canister
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tnk-table__imageMarineland Neutralizing Blend
  • Type of Filtration: Chemical (x2)
  • Material: Activated carbon and zeolite
  • Filter Style: HOB/Canister
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tnk-table__imageFluval Biomax Filter Media
  • Type of Filtration: Biological
  • Material: Ceramic
  • Filter Style: HOB/Canister/Sump
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tnk-table__imageSeachem Matrix Bio-Media
  • Type of Filtration: Biological
  • Type of Filtration: Biological
  • Filter Style: HOB/Canister/Sump
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tnk-table__imageAquaClear 70-Gallon Biomax Filter Insert
  • Type of Filtration: Biological
  • Material: Porous Inorganic Compound
  • Filter Style: AquaClear 70-Gallon BioMax Only
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Quick Guide To Filter Media

Seachem Laboratories 2

This can be a confusing topic because there are literally hundreds of products marketed as “aquarium filter medium,” and many of them seem to have nothing in common with each other. You’ll have to look at the specs for your filter to narrow down the likely candidates and identify the types that’ll work for your system.

Some products are designed to fit inside specific filtration systems, while others can be customized for use in nearly any type of filter. Before we can identify an ideal product for your tank, we need to talk about what the different types of media bring to the filtration game!

Types Of Aquarium Filter Media

The media is used inside filtration systems to remove physical debris and toxins from your aquarium water. Despite the vast array of media available, they all perform at least one type of filtration, and a few offer multiple types of filtration in a single product. There are three primary ways media can function to filter aquarium water:

Mechanical Filter Media

Whether you’re looking to filter freshwater or saltwater fish tanks, you’ll definitely need filter media that can mechanically remove any particles or debris floating in your water. This includes food scraps, solid fish waste (poop) and decaying plant material that can foul your tank and cause problems with water quality.

Beautiful planted tropical freshwater aquarium with fishes. Aquascape.

Coarse mechanical media is usually the primary type for a basic internal or HOB filter, or the first stage inside a premium system, while finer, more easily clogged media is used to remove microscopic particles further inside the filter. They include things like:

  • filter pads (may also be filled with chemical media)
  • top aquarium filter sponges
  • porous ceramic pre-filter rings
  • fine water polishing pads

Chemical Filter Media

With the chunky debris removed, your water will look cleaner but won’t necessarily be clear or safe for your fish. Organic materials from your substrate or decor may still discolor your water, and the waste from your animals can poison the tank. Chemical media can absorb toxins and remove any off-odors or colors in your water.

If you’ve ever used a water filter to eliminate the smell from tap water, or filtered cheap vodka through one to improve its flavor, then you can understand the purpose of this stage of filtration! Chemical media can go a long way to keeping your toxin levels low and your fish healthy. They include media such as:

Active coal for filters
  • Activated carbon chips or formed pellets that remove tannins and organic materials from the water and neutralize odors.
  • Rocks or chips formed from ammonia-absorbing resins.
  • Natural minerals like Zeolite that absorb toxins like ammonia and nitrate.

Biological Filter Media

After mechanical and chemical filtration, what’s left for filter media to do? It depends on the type of filter, as many don’t have a special stage for this, but some also hold long-lasting biological filtration media. Bio-media is porous and provides a lot of surface area to maintain colonies of good bacteria inside your filter.

You should already have a decent population of detoxifying bacteria in the substrate if you’ve properly cycled your tank, but you really can’t have too much biofiltration in an aquarium. The best bio-media for your aquarium will depend on your set-up. You may not want to sacrifice the space needed to hold this type inside a small or basic filter.

But for premium HOB and canister systems, biofiltration media makes a lot of sense. The bacteria will keep your ammonia levels down and provide nutrients for your live plants to use. You’ll definitely need this type of media for aquarium sumps on saltwater and reef tanks. Bio-media is a very diverse type and may include:

Seachem Laboratories Matrix
  • Porous ceramic media like rings, disks or cylinders.
  • Inert porous materials usually resembling small rocks.
  • Hollow plastic or foam balls, stars or cylinders (may also hold chemical media).
  • Glass balls, disks, rings or splinters.
  • Long-lasting, thick coarse sponge-like pads.

How To Use Filter Media

Even within the three types, you can see there is a great deal of diversity when it comes to filter media. How you use the media you’ve chosen will depend greatly on how customizable your filtration system is. Inexpensive systems that use pre-made inserts or cartridges are not always easy or even possible to adjust in this fashion.

Most high-end internal and HOB filtration systems allow for at least a bit of customization, and canister filters, with their multiple media baskets, are the most customizable next to aquarium sump systems.

Arrangement In Filter Stages

What order should you place the filter media in the filter? Your system’s manual will direct you towards the ideal arrangement, and you should pay attention to their recommendations. Placing media in the wrong place inside your filter could cause problems with its operation, depending on the type of filter you’re using.

care for a filter for an aquarium

Using a fine water polishing pad in the first stage of a HOB filter, for instance, could cause it to quickly clog and force the water to by-pass the other stages or backflow into your tank. Course pads, sponges and loose media work better for the first stage of debris filtration. Here are some guidelines to follow:

  • Use coarser mechanical filtration media in the initial stage(s) to remove large debris and allow water to keep flowing unobstructed to the other stages, especially in HOB filters.
  • Chemical filtration media is usually used along with mechanical or in a separate stage after the large debris have been removed.
  • Premium HOBs and most canister filters also use fine mechanical filtration media in later stages to polish the water and remove microscopic particles.
  • Biological filtration media is best used as a final stage, once the water is clean and fully oxygenated. This will maximize the detoxifying effects of the bacteria.

Cleaning Filter Media

How do you clean filter media? It depends on the type. Mechanical media like filter pads, sponges and pre-filter ceramic rings can be rinsed gently under running water until they look clean, and then reused inside your filter. I usually do this once a week to once a month, or whenever I’m maintaining my filtration system.

cleaning the filter for the aquarium

However, this may kill any good aquatic bacteria growing on them. You can’t wash your bio-media in this fashion or the chlorine in the tap water will wipe-out your bacterial colonies and you’ll lose all your biofiltration. Instead, gently rinse this type of media in a bucket with some of your aquarium water when it looks dirty.

Changing Filter Media

Notice I skipped how to clean chemical filtration media. That’s because the majority of these types can’t be cleaned and reused. Instead, you’ll have to replace it.

  • Activated carbon should be replaced about every 3 weeks.
  • If you’re using a blend of carbon that includes an ammonia absorbing media, replace them both on the same schedule.
  • Some toxin-absorbing resins and zeolite products can be reused as long as they are not mixed with activated carbon, but you’ll have to check the instructions on the package to know how to clean and rejuvenate the media.

Filter pads and sponges of all types can usually be cleaned and reused until they are nearly threadbare, but biological media is even more long-lasting.

Aquarium filter media in bowl over white backgdround
  • You only need to replace bio-media if it starts to break down or crumble in the filter, so you should get at least 6-month use from a batch and likely more.
  • In these cases, replace no more than ½ the media with fresh stuff and give the bacteria a few months to get established before swapping out the old ½.

How To Choose The Ideal Media For Your Filter

Now you know the details of the various types of media and how to use them, but how do you go about picking the best media for your particular filtration system?

What Type Of Filtration Do You Need?

The place to start is by examining your aquarium so you can fix whatever is lacking in your current set-up. Do you need to remove big debris or polish the water a bit more? Then improving your tank’s mechanical filtration could be the goal. If your water is murky or smelly, then more activated carbon might do the trick.

For tanks with a high bioload, like goldfish tanks, or those with sensitive fish or a lot of live plants, you may need the extra power of an ammonia-removing media. That could mean using resins or zeolite in a media basket, or adding bio-media to your filter. The best option depends on your filtration system.

How Customizable Is Your Filter?

External filter for aquarium with media. Isolated vector illustration

Take a look at your filter and it’s instruction manual. Do you even have the option of going with a customized media set-up? Undergravel filters and most inexpensive internal types use pre-filled plastic cartridges. Unless you have a 3-D printer and some mad design skills you may not be able to modify their media arrangements.

Pre-Made VS Customized Pads And Media Mixes

While you can almost always modify the pads and at least the chemical media used in a HOB filter, it may not always make sense to do so. It can be easier to stick with the pre-made or branded filter pads. But high-end/large HOBs and canister filters often have extra media baskets, and you can easily pick the mix you use in those.

Media Size And Shape

Aquarium Filter Media Kits - CNZ

If you opt to customize, then you should take a close look at your media baskets. You want to pick a media type that’s large/coarse enough to allow water to easily flow through the basket. At the same time, you don’t want the media to slip out through the basket’s mesh and mess up your filter’s motor.

It’s becoming quite popular to sell filter media in mesh bags you can just place in your HOB or canister filter. The mesh contains the finer particles and prevents them from floating away with the water. But these mesh bags don’t always work well in HOBs because gravity pulls the media to the bottom instead of forcing water through it.

Filter Media: Product Round-Up And Reviews

It’s a challenge to point you to the ideal filter media because the best type(s) depends on the needs of your aquarium community and the limitations imposed by your filtration system. Here is a selection of popular filter media products to consider:

1. Fluval Pre-Filter Media

Fluval External Power Filter Pre-Filter Media
  • Type of Filtration: Medium to Coarse Mechanical
  • Material: Ceramic
  • Filter Style: Canister
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Fluval is definitely well-known for their premium filters, and these ceramic pre-filter cylinders are an ideal way to mechanically remove big debris from the water in your canister filter. Instead of using a coarse pad in the first stage, you’ll fill it with these hollow ceramic rings. They are similar to the ceramic Fluval media below but are smaller in size.

The filter’s motor forces water through the pile of rings, where debris gets collected. The advantage of these rings over a pad is they are less likely to get clogged. They also last much longer than filter pads and sponges and often work for years before needing replacement.

You can use this media in canister filters, even those not made by Fluval, but it won’t work for HOBs. Placing the rings in a mesh bag inside a HOB would allow the majority of the water to flow over the media, since gravity will pull them towards the bottom of the filter. You’d be better off going with a filter pad in those types.

Pros Cons
  • Long-lasting and efficient mechanical filtration
  • Won’t clog as easily filter pads and sponges
  • Easy to maintain and rinse clean
  • Won’t work with HOBs and may not be ideal for all canister filters
  • Only targets large debris and won't polish your water
  • Frequent cleaning and rinsing is needed to prevent clogs, so can’t really double as a bio-media

2. CNZ Aquarium Filter Media Kits

CNZ Aquarium Filter Media Kits
  • Type of Filtration: Chemical
  • Material: Compressed Carbon Cylinders
  • Filter Style: HOB/Canister
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If you’d like to add some chemical filtration to your filter but don’t want to deal with measuring bulk media, then these pre-filled bags of activated charcoal pellets could be the solution to your problem. The reusable mesh bags make it easy to rinse your charcoal and toss it right in your filter, where it can remove colors and odors from your aquarium water.

While CNZ makes top-quality ceramic media kits, I’m a lot less impressed with their charcoal pellets. Unlike the chips of activated charcoal in the Marineland media below, these are compressed into shape. They start to break down when you rinse them, and I found bits of charcoal floating in my water days after inserting them in my filter.

I’m also not convinced that these would work well in many HOB filters unless they were used in an internal media basket. The mesh bag isn’t very durable and can’t keep the media evenly distributed inside your filter, so water may flow around or over instead of through it. The bags could be helpful in a canister filter, however.

Pros Cons
  • Inexpensive and easy-to-use
  • Comes in pre-filled mesh bags, so no need to mess with bulk media
  • The cylindrical shape is ideal for maximum water exposure
  • Compressed carbon pellets are hard to rinse clean
  • The pellets break down quickly and don’t last very long
  • Mesh bag is not very durable and won’t hold media securely in place in most HOBs

3. Marineland Diamond Ammonia Neutralizing Blend

Marineland Diamond Blend Carbon Ammonia Neutralizing Carbon Filter Media
  • Type of Filtration: Chemical (x2)
  • Material: Activated carbon and zeolite
  • Filter Style: HOB/Canister
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If you’re looking to reduce the toxins in a goldfish tank or one with a lot of live plants or sensitive critters, then you should definitely consider using this premium media mix from Marineland. It’s a blend of activated carbon and zeolite chips which offers twice the filtration power. It neutralizes the ammonia and nitrates in your water and removes any discolorations or odors!

I used this mix in my planted community HOB filters for years and never had an ammonia spike or other water quality problem. The small chips are the ideal size and shape to maximize their contact with the water and they work with most customizable filtration systems.

The Marineland mix should easily fit in your media baskets and allow the water to flow through without a problem, and the particles won’t slip through and damage your equipment. Marineland also sells the activated carbon and zeolite media separately if you prefer to use them in different stages. In terms of quality, this is one of the best!

Pros Cons
  • Ideal size and shape for maximum absorption and cleaning power
  • Bulk media mix allows for flexible use in HOB/canister filters
  • Neutralizes toxic ammonia and nitrites plus acts as a water odor/discoloration remover
  • Requires you to measure and distribute the media in baskets or mesh bags inside your filter
  • Requires monthly replacement and can’t be cleaned and reused
  • Premium product comes with a premium price

4. Fluval Biomax Filter Media

Fluval Biomax Filter Media
  • Type of Filtration: Biological
  • Material: Ceramic
  • Filter Style: HOB/Canister/Sump
Check The Price

I mentioned this product above in the other Fluval review, but if you’d like the best in bio-filtration then take a look at these large ceramic cylinders! Designed to support thriving populations of good aquatic bacteria, the hollow rings allow them to spread throughout the media and provide a lot of detoxifying power to your filter.

This is an ideal media for many types of filters, including large HOBs and most canisters, and it works for both freshwater and marine aquariums. You could even use these rings in your sump system, although the Seachem product below would be a better option. They are durable and extremely long-lasting, too.

I prefer this type of ceramic bio-media over the plastic or glass styles, but in some situations, it may not be ideal. Ceramic becomes more fragile as it ages, so you’ll have to be careful when cleaning the media. You’ll also have to wash it with aquarium water to protect the bacteria from chlorine and other chemicals in tap water. It’s still one of, if not the best, bio-media on the market!

Pros Cons
  • Durable and long-lasting ceramic cylinders provide years worth of biofiltration
  • Works in HOB, canister and aquarium sump filters
  • Porous hollow ceramic shape ideal for biofiltration because bacteria can grow into the media
  • Harder to maintain than mechanical or chemical media
  • Ceramic is durable but eventually breaks down and becomes more fragile with time
  • Basically the same as other Fluval media, just a different size/shape

5. Seachem Matrix Bio-Media

Seachem Laboratories Matrix
  • Type of Filtration: Biological
  • Material: Porous Inorganic Compound
  • Filter Style: HOB/Canister/Sump
Check The Price

While I’m a huge fan of the Fluval bio-media, I’m also the first to admit that it may not be the best choice for every filtration system. If you’d prefer a media that you’ll never need to replace, then consider this premium option from Seachem. Made from porous inorganic compounds, these pebbles allow bacteria to grow inside the media as well as on the surface!

While the Seachem works in HOB and canister systems, it’s really designed for aquarium sump filters. These slow trickle-style filters allow aquarium water to spend a lot of time flowing through the media while exposed to oxygen, which increases the efficiency of the bio-media. You won’t see the same performance in a HOB or canister filter, unfortunately.

While it may not be the best for every situation, if you’re running a sump then this is the media I’d go with, even if it’s more expensive initially. The fact that you’ll never need to replace it balances things out in the end. I’ve also used this product successfully in a canister filter on a turtle set-up, so it’s certainly flexible to use!

Pros Cons
  • Won’t crumble or break down and never needs replacing
  • Ideal for aquarium sump filters
  • Highly porous surface allows bacteria to grow inside and out
  • Very dusty product and requires a lot of rinsing if used in HOBs or canister filters
  • Small particle size may require a mesh bag for some systems
  • Initial investment may be pricey depending on how much you need to fill your filter

6. AquaClear 70-Gallon Biomax Filter Insert

Aquaclear A1373 70-Gallon Biomax,White
  • Type of Filtration: Biological
  • Material: Porous Inorganic Compound
  • Filter Style: AquaClear 70-Gallon BioMax Only
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If you’re using one of our highly rated AquaClear filters and want to opt for the easiest choice in biofiltration, then these branded filter inserts could be the ideal choice for your tank! Unlike many, the AquaClear HOB is designed with biofiltration in mind. This media comes wrapped in a mesh bag, so all you have to do is pop it in your filter!

This insert fits in the top of your filter, just above the water polishing sponge where it gets maximum exposure to oxygen. While it might be an awkward fit in other HOBs, the AquaClear’s design won’t allow the water to flow around or bypass the bio-media stage. The noodle-shaped inorganic compound allows a lot of surface area for bacterial growth.

AquaClear recommends replacing the bio-media every 3 months, which would drastically reduce the efficacy of the biofiltration and could lead to dangerous ammonia spikes. Frankly, I ignore that rule myself. Instead, I only replace this media when the mesh bag or particles start to break down. Monthly rinsing in aquarium water kept it working without a problem, but this is one of those personal calls.

Pros Cons
  • No fuss, just toss in the top of the filter!
  • Ideal type of bio-media for AquaClear HOB filters
  • Long-lasting media comes in pre-filled mesh bags
  • Manufacturer recommends replacement after 3 months
  • Only fits branded filter and not ideal for other HOBs, although it could be used in canister filters
  • Pricey option if replaced every 3 months as recommended


Best Filter Media

Don’t let the diversity of filter media products fool you; picking the ideal type isn’t hard once you know how they work and which operate best with your filter. In most cases, you’ll have a lot of options between branded, pre-filled inserts and bulk media mixes. We’d love to hear about your media choices, so please comment below or on social media!

If you’re still not sure which products to choose, consider the following:

For chemical filter media, I’d pick the Marineland carbon and zeolite mix. It’s simply one of the best options on the market, and the price and value are outstanding. If you’d like to add bio-filtration to your HOB or canister filter, the Fluval Biomax is an ideal choice unless you have an AquaClear filter, in which case I’d go with the branded insert. For aquarium sump filters, I’d pick the Seachem over the Fluval, however.

If you have a canister filter and would like to replace your filter pad with a more durable and longer-lasting mechanical option, then the Fluval pre-filter media could be the best choice for you!

Jen has more than 30 years experience as a biologist, aquarist, and fishkeeper. She is an expert in setting up new tanks and maintaining naturally-planted freshwater habitats, and has experience raising a wide variety of aquatic species.

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