Finding The Best Canister Filter Media – Reviews & Buyers Guide

If you want to keep your tank fresh and clean, what's one of the most affordable and efficient methods around? Most dedicated aquarium owners know that an external filter loaded with the best canister filter media is the savviest option. Making your selection of these media, however, is another ballgame entirely.

There's a bevy of options out there, and it seems to be in a constant state of growth. Should you go with your filter's branded media, or a third-party option? Even within those categories, there are many styles of mechanical, chemical, and biological media available. Some work better with salt water, others with freshwater. Some are ideal for turtles, others for fish, and others also work well with both.

Top 5 Canister Filter Media Comparisons


Media Type



Our Score

Fluval BioMax Rings

Biological Filtration

500 grams


Two Little Fishies ATLB2 PhosBan

Chemical Filtration

150 grams


Marineland Black Diamond Activated Carbon

Chemical Filtration

1134 grams


Coralife Pure Flo Filter Pad, 100 Micron

Mechanical Filtration

136 grams


CNZ Bio-Balls

Biological Filtration

113 grams


Regardless of your tank's specifics, you want to get the best media for canister filters available, so I've assembled some of the best around to take a closer look.

Media Matters

If you've had your tank for any period, you already know the basics: biological, chemical, and mechanical media are what your tank water passes through within a filter to become purified. In general, mechanical filters remove fish excrement and large particles; biological media are home to bacteria colonies that primarily handle excess ammonia, and chemical filtration negates the effects of other specific compounds within the water. Did you know that there are more than one of each type of media, though?

Mechanical Media

For mechanical media, you have options like Bio-Glass: small, porous cylinders crafted from silicate that weeds out large debris. It's easy to clean and serves a dual purpose of also providing a surface for beneficial bacteria (so it doubles as biological filtration as well).

There are finer options like filter pads, thin pieces of cloth-like material that can be cut to your desired size. They trap particles and can be easily sandwiched between other kinds of media if you have a filter with a large central chamber that allows you to install multiple media types. Micron filters offer an even finer version of the same type of filtration action, while still allowing biological agents to pass through them freely. Best of all they are usually machine washable and can be reused again and again.

You also have an option known as filter floss, a thicker, spongy, poly-blend material that catches detritus while still allowing maximum water flow through a filter. These are a great option for power users who want to keep their GPH flow rates high while running their canister.

Biological Media

All biological media are designed with the goal in mind of maximizing the surface area upon which bacteria can grow, and promoting the growth of said bacteria. These typically come in either ring or ball form. The Bio Glass above is one such option, as are ceramic rings designed to be extremely porous to aid water flow.

Bio Balls and their close relatives Bio Globes, are polypropylene spheres designed to compress to maximize space saving and keep flow rates high. This allows users to pack them in without suffering losses in filter performance. They don't provide quite the same amount of surface area as rings and glass, but they are less likely to become jammed, and rarely (if ever) need to be replaced. They also help with ammonia levels before bacterial consumption, meaning the bacteria on these media needn't work as hard to handle high loads.

Chemical Media

This is where the levels of diversity become very intense. One of the more popular varieties of chemical filtration is Activated Carbon. Which can tackle harmful elements dissolved in the water (copper, chlorine, etc.) It can also remove some quantities of drugs (pharmaceuticals and medications) and reduce amounts of overall water discoloration.

Excessive levels of phosphorus in tank water can cause algae to grow unchecked, and potentially kill your fish. Phosphate removers, which fit into media bags very similar to carbon, can mitigate the buildups and keep your aquarium healthy. They are particularly useful in situations where a protein skimmer may not be as helpful, such as a freshwater tank.

There is a broad range of other products that can be used to neutralize chemically harmful compounds, which include synthetic polymers (which can be utilized like carbon but have the added benefit of regenerating themselves), and Ion Exchange Resins (man-made or naturally occurring compounds that attract chemicals with a light charge). They can be used solo, or combined with carbon to augment its effects on the water.

Media Care

Regular maintenance is required to keep both a filter and some of its contained media working properly. You may have to periodically remove and wash your media to keep it working at optimal efficiency. With that in mind, you'll likely be better served obtaining media that can be used over and over, is easy to clean, and doesn't have to be cleaned too often.

When washing biological media, however, one must take care not to kill the beneficial bacteria that have made the media filter their home. Instead of hot tap water, it is recommended that they are cleaned with a bucket of water from the aquarium where they live. More than a few novices have made this mistake, and subsequently beat their heads against the wall for hours in shame.

Filter Media For Canisters Reviews

Fluval BioMax Rings

  • 500 grams
  • Biological filtration

Fluval is well known in the filter and media game, and their BioMax filter media, which can be used with fresh and saltwater tanks, provide an excellent surface for bacterial growth. Rings, in general, provide a large surface area, and the porous nature of these particular rings increases that space even further. The cylinders measure about 5/8" x 3/4" each, and can be optimized by using them as the last step in your filtration process.

These rings are particularly durable and need only be replaced when they start to crumble. Unfortunately, they start to crumble quicker than some other rings. Still, you can keep them going for six months or even longer in some cases, which is ideal for tank owners like me who aren't exactly thrilled about tinkering with the filter every month or so. That being said, cleaning and replacing isn't a huge chore. You can clean these with a dunk or two in some tank water and keep it moving!

​The extra texture on the Fluval rings not only aids water filtration, it significantly promotes bacterial growth, meaning you'll see results faster. Fluval isn't stingy about quantity either. In the standard 500 gram pack you get a lot of rings (100 approx.), enough to last several cycles at least.


  • Large surface area
  • Plenty of media per pack
  • Work fast
  • Don't greatly inhibit flow rate


  • Crumbly

Two Little Fishies ATLB2 PhosBan

  • 150 grams
  • Chemical Filtration

Designed for removing excess phosphorous from tank water, PhosBan uses synthetic ferric oxide hydroxide grains to absorb the element from the water. It can be used exactly like activated carbon, just throw it in the filter bag and drop it in your filter tray or canister. PhosBan is non-toxic and doesn't leach any compounds back into your tank water.

It can be used with saltwater and freshwater tanks, and also removes silicate, arsenic, and water discoloring compounds from the water.​

You'll need to be careful with the amount you use, however, as too much can strip your aquarium of the necessary amount of phosphorous that your tank needs to support life. The grains are fragile, so they shouldn't be stirred or handled roughly. This also means that they can't be used with extremely high flow rates, as that would pulverize the grains, rendering them much less useful. It's best to use these with an up flow canister filter.

It also has a tendency to conglomerate, which reduces its efficiency and can impede the flow of water through your canister filter. There's also the fact that the standard container, 150 grams, is only enough for a few changes. It does, however, have a long shelf life (3 years) as long as you keep the container sealed tight.


  • Excellent filtration capacity
  • Works for both salt and freshwater
  • Works for removing other compounds as well


  • Granules are very fragile

Marineland Black Diamond Activated Carbon

  • 1134 grams
  • Chemical Filtration

For advanced chemical filtration, Marineland activated carbon is one of the best filter media for canister filters around. Long lasting, heat-activated, and specially sized (small granules) proves more efficient than other forms of carbon.

This activated carbon is ideal for taking odors, discoloration, and various toxic chemicals from tank water. It's more compatible with freshwater aquariums (due to the ammonia neutralization agent being ineffective in saltwater), but it's very efficient at doing its job.

You'll have to replace this more often than some other chemical media, but Marineland provides a significant amount (1134 grams) for your money. It's also fast acting, showing results in your tank within a few days. It doesn't require much in the way of washing, and doesn't grind down to dust like some other carbon brands are prone to doing.

Marineland carbon will also handle excess copper and other elements in the water. This is a highly effective product and can be coupled with other forms of chemical media or used as a standalone. In general, users won't have to worry about the carbon breaking apart or clogging their filter impeller. Just remember to use this carbon as intended (in a media bag in your filter). Some creative users like to utilize this as a multi-use product, but it shines brightest when filtering chemicals from your tank.​


  • Great value
  • Fast acting
  • Durable media


  • Has to be replaced more frequently

Coralife Pure Flo Micron Filter Pad

  • 18” x 30”
  • Mechanical Filtration

These micron filter pads provide ultra-fine mechanical filtration for canister filters and are a highly efficient and versatile method of doing so. Their superbly fine pores trap concrete debris (including tiny bits and pieces), while still allowing the passage of water and beneficial bacteria to maintain optimum aquarium health and clean water in both saltwater and freshwater tanks.

Constructed from a nylon-polyester blend, Coralife Pads are durable, long-lasting, and 100% reusable. They will require periodic cleaning, sometimes with bleach and chlorine, but are well worth it for continued use. They come packaged in oversized sheets, and can be cut down to meet your filter's particular specification. This makes them not only highly compatible with different filter types, but with different filter media types as well. It's a great option for usability, but a bit of a hassle for clumsy types like yours truly.

This also allows Coralife to give you plenty of bang for your buck. The standard 18" x 30" pad is more than enough to last for many uses. They clog quickly, but that's what you want out of your mechanical media (if it's not trapping particles, what good is it?). It's one of the most well known and potent mechanical filtration media on the market and for good reason.​


  • Ultra-fine
  • 18” x 30”
  • Mechanical Filtration


  • Will have to wash frequently

CNZ Bio-Balls

  • 26mm, 50-count
  • Biological Filtration

Bio-Balls are the most long-lasting and durable of all biological filter media and provide ample room for beneficial bacteria growth with supreme ease-of-use. As they do not require replacement unless they are damaged or destroyed, a single pack could potentially last you longer than the lifespan of some of your fish. CNZ Bio-Balls are 26mm in diameter, capable of compressing to allow for tight packing, and include an interior Bio-Sponge to create an even greater surface area for bacterial propagation.

​As they are small, you may need to order multiple packs if you have a larger tank, but they are quite reasonably priced, so you're in no danger of breaking the bank. Their design allows for high flow rates and maximum functionality of your filter, and they will only need to be cleaned if heavily clogged. In such cases, a dunk in some tank water will have them back to working at peak efficiency.

To prevent clogging, using these at the end of your filtration cycle is the best strategy. After your mechanical filtration has removed debris that could potentially become stuck in the Bio-Balls, the bacteria can make short work of any extra nitrates or nitrites that have built up in your tank's water supply.


  • Long lasting
  • Easy to clean
  • Affordable


  • May need multiple packs for large tank


Your precise media will vary based on your individual tank specifications and what aquatic life you have housed within, but if you're looking to purchase highly adequate media with excellent longevity, the CNZ Bio-Balls are a difficult option to top.

In addition to being easy to install and maintain, they rarely require much in the way of upkeep, will not need to be replaced until broken, and, when used properly, will hardly ever jam on you. You'll have to combine them with other media types for overall tank cleanliness, but regarding the media that will bring the most value to your aquarium, these Bio-Balls are the way to go.

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