The best filter media for a healthier aquarium

Learning about aquarium filters can be a dizzying prospect, and that’s just searching for the perfect gear for your tank! However, once you have your system installed, you will be faced with the next challenge: identifying the best filter media to use inside! Let’s explore these products and identify the ideal type for your tank!

Quick Guide to Filter Media

This can be a confusing subject because there are literally hundreds of products marketed as “aquarium filter media” and many of them seem to have nothing in common with one another. You’ll need to look at your filter specifications to narrow down the possible candidates and identify the types that will work for your system.

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

Types of filter media for aquariums

The medium is used within filtration systems to remove physical debris and toxins from your aquarium water. Despite the wide range of media available, all perform at least one type of filtration, and some offer multiple types of filtration in a single product.There are three main ways media can work 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 (droppings), and decaying plant material that can foul your tank and cause water quality problems.

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

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

chemical filter media

Once the coarse debris is removed, the water will look cleaner, but it won’t necessarily be clear or safe for fish. Organic materials from your substrate or décor can still discolor your water, and waste from your animals can poison the tank. Chemical media can absorb toxins and remove bad odors or colors from the water.

If you’ve ever used a water filter to remove odor from tap water, or filtered cheap vodka through one to improve its taste, then you can understand the purpose of this stage of filtration! Chemical media can be of great help in keeping toxin levels low and keeping fish healthy. They include means such as:

  • Activated carbon chips or formed granules that remove tannins and organic materials from the water and neutralize odours.
  • Rocks or chips formed from ammonia-absorbing resins.
  • Natural minerals such as zeolite that absorb toxins such as ammonia and nitrate.

Biological filter media

After mechanical and chemical filtration, what is left for the filter media to do? It depends on the type of filter as many do not have a special stage for this, but some also contain long life biological media. Biological media is porous and provides a large surface area to maintain colonies of good bacteria within 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 biological media for your aquarium will depend on your setup. You may not want to sacrifice the space needed to keep this type inside a small or basic filter.

But for premium HOB and vessel systems, biofiltration media makes a lot of sense. The bacteria will keep your ammonia levels low and provide nutrients for your living plants to use. You will definitely need this type of medium for aquarium sumps in reef and saltwater tanks. Biomedia are of a very diverse type and can include:

  • Porous ceramic media such as rings, discs or cylinders.
  • Inert porous materials that often resemble small rocks.
  • Balls, stars or hollow cylinders of plastic or foam (may also contain chemical media).
  • Glass balls, discs, rings or chips.
  • Thick, thick and durable, sponge-like pads.

How to use filter media

Even within the three types, you can see that there is great diversity when it comes to filter media. How you use the media you have chosen will largely depend on how customizable your filtration system is. Inexpensive systems using prefabricated inserts or cartridges are not always easy or even possible to fit in this way.

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

Filtration staging

In what order should you place the filter media in the filter? Your system manual will guide you to the ideal layout, and you should heed its recommendations. Placing the media in the wrong place inside your filter could cause problems with its operation, depending on the type of filter you are using.

Using a fine water polishing pad on the first stage of a HOB filter, for example, could cause it to clog quickly and force water to bypass the other stages or backflow into your tank. Pads, sponges, and loose media work best for the first stage of debris filtration. Here are some guidelines to follow:

  • Use a coarser mechanical filtration media in the initial stages to remove large debris and allow water to continue to flow unobstructed to other stages, especially on HOB filters.
  • Chemical filtration media are usually used in conjunction with mechanical media or in a separate stage after large debris has 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 is the filter media cleaned? It depends on the type. Mechanical media such as filter pads, sponges and ceramic pre-filter rings can be gently rinsed under running water until they appear clean and then reused inside the filter. I usually do this once a week or once a month, or whenever I service my filtration system.

However, this can kill any good aquatic bacteria growing on them. You cannot wash your biological media this way or the chlorine in your tap water will kill your bacterial colonies and you will lose all your biofiltration. Instead, gently rinse this type of medium in a bucket with some water from your aquarium when it looks dirty.

Change of filter media

Notice that I skipped how to clean the chemical filter media. That’s because most of these types cannot be cleaned or reused. Instead, you will have to replace it.

  • Activated charcoal should be replaced approximately every 3 weeks.
  • If you are using a charcoal mix that includes an ammonia absorbing medium, replace them 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 will need to refer to the package instructions for how to clean and rejuvenate the medium.

Filter pads and sponges of all kinds can be cleaned and reused until almost worn out, but biological media is even more durable.

  • You only need to replace the bio media if it starts to break down or crumble in the filter, so you should get at least 6 months’ use out of a batch and probably more.
  • In these cases, replace no more than half of the medium with fresh material and give the bacteria a few months to become established before changing the old half.

How to choose the ideal media for your filter

Now you know the details of the different types of media and how to use them, but how can you choose 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 missing from your current setup. Do you need to remove the large debris or polish the water a little more? So improving your tank’s mechanical filtration could be the goal. If your water is cloudy or smells bad, then more activated carbon might be enough.

For tanks with a high biological load, such as goldfish tanks, or those with sensitive fish or many live plants, you may need the added power of an ammonia removal medium. That could mean using resins or zeolite in a media basket, or adding biomedia to your filter. The best option depends on your filtration system.

What level of customization does your filter have?

Take a look at your filter and its instruction manual. Do you have the option to opt for custom media settings? Gravel filters and cheaper internal types use pre-filled plastic cartridges. Unless you have a 3-D printer and some crazy design skills, you may not be able to modify your media layout.

Premade VS Custom Media & Pad 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 may be easier to stick to brand name or pre-made filter pads. But large/high-end HOBs and canister filters often have additional media baskets, and you can easily choose the mix you use in them.

Media size and shape

If you opt for customization, then you should take a close look at your media baskets. You want to choose a type of media that is large/thick enough to allow water to easily flow through the basket. At the same time, you don’t want the media to leak through the mesh of the basket and mess up your filter motor.

It is becoming quite popular to sell filter media in mesh bags that you can put in your HOB or canister filter. The mesh contains the finest particles and prevents them from floating 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 Overview & Reviews

Pointing you to the ideal filter media is challenging because the best type depends on the needs of your aquarium community and the limitations imposed by your filtration system. Below is a selection of popular filter media products to consider:

1. fluval prefilter media

  • Filtration type: medium to coarse mechanical
  • Material: Ceramic
  • Filter Style: Canister

Fluval is definitely known for its premium filters, and these ceramic pre-filter barrels are an ideal way to mechanically remove large debris from the water in your canister filter. Instead of using a thick pad in the first stage, you’ll fill it with these hollow ceramic rings. They are similar to the fluval ceramic media below, but are smaller in size.

The filter motor forces water through the ring stack, where debris collects. The advantage of these rings over a pad is that they are less likely to clog. They also last much longer than filter pads and sponges, often working for years before needing replacement.

You can use this media in canister filters, even those not made by Fluval, but it will not work for HOBs. Placing the rings in a mesh bag on a counter top would allow most of the water to flow over the media as gravity will pull them to the bottom of the filter. It would be better to opt for a filter pad of those types.


  • Efficient and durable mechanical filtration
  • It doesn’t get clogged as easily with filter pads and sponges.
  • Easy to maintain and rinse.


  • Will not work with HOB and may not be ideal for all canister filters
  • It only targets large debris and does not polish your water
  • Frequent cleaning and rinsing is needed to prevent clogging, so it cannot function as a biological media.

2. CNZ Aquarium Filter Media Kits

  • Filtration Type: Chemical
  • Material: compressed carbon cylinders
  • Filter Style: HOB / Canister

If you want to add some chemical filtration to your filter, but don’t want to deal with bulk media metering, these pre-filled bags of activated carbon granules could be the solution to your problem. Reusable mesh bags make it easy to rinse the carbon and throw it right into the filter, where it can remove colors and odors from your aquarium water.

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

I’m also not convinced that they will work well in many HOB filters unless 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 can flow around or over it instead of through it. However, the bags could be useful in a canister filter.


  • Economical and easy to use
  • Comes in pre-filled mesh bags, so there’s no need to mess with bulk media
  • The cylindrical shape is ideal for maximum exposure to water.


  • Compressed carbon granules are difficult to rinse.
  • The granules break down quickly and don’t last long.
  • Mesh bag is not very durable and does not hold media securely in place on most HOBs

3. Marineland Diamond Ammonia Neutralizing Blend

  • Filtration Type: Chemical (x2)
  • Material: activated carbon and zeolite.
  • Filter Style: HOB / Canister

If you’re looking to reduce toxins in a goldfish tank or one with lots of live plants or sensitive creatures, then you should definitely consider using this premium media mix from Marineland. It is a mixture of activated carbon and zeolite chips that offers twice the filtration power. Neutralizes ammonia and nitrates in the water and removes any discoloration or odor.

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 your contact with the water and work with most custom filtration systems.

The Marineland mix should fit easily into your media baskets and allow water to flow smoothly, and particles won’t slide off and damage your gear. Marineland also sells activated carbon and zeolite media separately if you prefer to use them at different stages. In terms of quality, this is one of the best!


  • Ideal size and shape for maximum absorption and cleaning power.
  • Bulk media blending allows for flexible use in HOB/canister filters
  • Neutralizes toxic ammonia and nitrites and also acts as an odor/discoloration eliminator for water.


  • Requires you to measure and distribute media into baskets or mesh bags inside your filter
  • Requires monthly replacement and cannot be cleaned or reused
  • The premium product comes with a premium price

4. fluval Biomax filter media

  • Filtration Type: Biological
  • Material: Ceramic
  • Filter Style: HOB / Canister / Sump

I mentioned this product earlier in the other Fluval review, but if you want the best in biofiltration, check out these great ceramic cylinders! Designed to support thriving populations of good aquatic bacteria, the hollow rings allow them to spread throughout the media and provide a great deal of detoxifying power to your filter.

This is an ideal media for many types of filters, including large HOBs and most canisters, and 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 choice. They are also durable and extremely durable.

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


  • Durable, long-lasting ceramic cylinders provide years of biofiltration
  • Works on HOB sump, canister and aquarium filters
  • Porous hollow ceramic shape ideal for biofiltration because bacteria can grow in the media


  • More difficult to maintain than mechanical or chemical means
  • Ceramic is durable but eventually breaks down and becomes more brittle over time.
  • Basically the same as other Fluval media, just a different size/shape

5. Seachem Matrix Biomedia

  • Filtration Type: Biological
  • Material: porous inorganic compound
  • Filter Style: HOB / Canister / Sump

While I am a huge fan of Fluval Biological Media, I am also the first to admit that it may not be the best choice for all filtration systems. If you prefer a media that you’ll never need to replace, consider this premium option from Seachem. Made of porous inorganic compounds, these pebbles allow bacteria to grow both inside the medium and on the surface.

While the Seachem works in HOB and canister systems, it is actually designed for aquarium sump filters. These slow trickling filters allow the aquarium water to spend a lot of time flowing through the media while being exposed to oxygen, increasing the efficiency of the biomedia. Unfortunately, you won’t see the same performance in a canister or HOB filter.

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


  • Will not crumble or break and never needs to be replaced
  • 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 HOB or cartridge filters
  • Small particle size may require mesh bag for some systems
  • Initial investment can be expensive depending on how much you need to fill your filter

6. 70 Gallon Biomax Aquaclear Filter Insert

  • Filtration Type: Biological
  • Material: porous inorganic compound
  • Filter Style: BioMax 70 Gallon Aquaclear Only

If you are using one of our highly rated aquaclear filters and want to go for the easy option in biofiltration, then these brand name filter inserts could be the ideal choice for your tank! Unlike many, the AquaClear HOB is designed with biofiltration in mind. This medium comes wrapped in a mesh bag, so all you have to do is pop it into your filter!

This insert fits on top of your filter, just above the water polishing pad, where you get the maximum oxygen exposure. While it may be an awkward fit on other HOBs, the AquaClear’s design will not allow water to flow through or bypass the bio-media stage. The noodle-shaped inorganic compound allows a large surface area for bacterial growth.

AquaClear recommends replacing biological media every 3 months, which will drastically reduce biofiltration efficiency and could lead to dangerous ammonia spikes. Frankly, I myself ignore that rule. Instead, I only replace this media when the mesh bag or particles start to break down. Monthly rinsing with aquarium water kept it running smoothly, but this is one of those personal calls.


  • No hassle, just snap on the top of the filter!
  • Ideal type of biomedia for AquaClear HOB filters
  • Durable media comes in pre-filled mesh bags


  • The manufacturer recommends replacement after 3 months.
  • Will only fit brand filter and not ideal for other HOB’s although could be used on canister filters
  • Expensive option if replaced every 3 months as recommended


Don’t be fooled by the diversity of filter media products; Choosing the ideal type is not difficult once you know how they work and which one works best with your filter. In most cases, you’ll be spoiled for choice between brand name preloaded inserts and bulk media mixes. We’d love to hear about your media options, 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 would choose Marineland’s carbon and zeolite mix. It’s simply one of the best options on the market, and the price and value are exceptional. If you want to add biofiltration to your HOB or canister filter, the fluval Biomax is an ideal choice unless you have an AquaClear filter, in which case I would go for the brand name insert. However, for aquarium sump filters I would choose the Seachem over the Fluval.

If you have a canister filter and would like to replace your filter pad with a more durable mechanical option, then fluval pre-filter media might be the best option for you.

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