The Fish Keeping & Aquarium Guide.

Best Bio Filter Media For Freshwater Aquarium

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What is Biological Filter Media?

Biological filtration media is the best natural filtration method. It supersedes other filtration methods to help to remove harmful substances from an aquarium.

Bio-filter is a common term that is related to the purification of water carried out by bacteria. The biological filter creates to accommodate good bacteria colonies and increase their growth. When this happens, they end up eating up the harmful chemicals from the surrounding, thereby improving your fish’s quality of life.

Best Biological Filter Media For Freshwater Aquarium

Many manufacturing companies will always say that they have the best filter for sale. However, we chose these options after thorough research.
One vital thing to always remember is that you have to ensure that your bacteria media thrive well in the aquarium since your bio-media has bacterial colonies.

We will be discussing the six best bio media for your aquarium that you should invest in to help you invest in the ideal bio-media.

1) Eheim Substrat Pro

A German company produces Eheim Substrat pro made with sintered glass, whereby fine glass particles reduce into porous beads.

The sintering process may control the bead’s porosity. The product comes with an open structure that enables water to enter the media easily. As a result, biologically filtering the water will be much easier because of the bacteria colony’s rapid growth.

The Eheim Substrat pro can be reused through light rinsing with aquarium water every 30-90 days. If you think this isn’t good for the aquatic environment, you can replace it every 90 to 180 days.

The product is made for their various canister filters while using the beads in different kinds of canister filter tray. The Eheim Substrat Pro is specifically for large canister filters that have enough space for the beads. It is also the best option for marine and freshwater fish aquariums.


  • You can rinse the bead when cleaning them.
  • It helps to remove ammonia, nitrite, and nitrate.
  • It works with both marine and freshwater aquariums.
  • The inert glass is built very strong to prevent it from breaking down in the aquarium.


  • It is quite expensive.

2) Seachem Matrix Bio Media

The Seachem Matrix is a biological media created with strong pumice. It comes with a coarse surface that improves bacteria growth and promotes effective biofiltration in an aquarium.

According to the manufacturers, a liter of Seachem Matrix produces 170 liters of plastic balls. It provides both internal and external surface area designed for the growth of denitrifying and nitrifying bacteria. A liter of Seachem Matrix media is for ten gallons of water without affecting the system’s pH value.

The product is solid to avoid breakdown. So, you shouldn’t be bothered about losing filtration capacity or the need for any replacement. You can place the product in any filter, but it is more effective in canister filters. It is large enough and doesn’t require any filter bag for its applications.


  • It can use for long periods without being replaced.
  • It doesn’t require a filter bag.
  • It removes and controls ammonia, nitrate, and nitrite.
  • You can rinse it whenever you want without causing damage to the filter or causing harm to the bacteria.
  • It comes with a very large surface area.
  • It is highly porous.


  • You may have to use a bigger pond Matrix if you’re using the drip tray system.

3) Fluval Biomax Filter Media

This product contains aluminium oxide and silica that forms a porous ring.
The Fluval BioMax provides a large surface for your aquarium’s biological filtration to leave space for colonization of denitrifying and nitrifying bacteria.

It has enough space than many filter media, and there is a hole in the middle that allows easy flow of water throughout the media. It is to enable optimal contact time for effective biological filtration.


  • It can serve as a loose bio-media in a canister filter.
  • The surface creates to be very porous to enable the growth of good bacteria.
  • The product is not expensive.
  • Excellent for denitrification and nitrification.
  • Long-lasting and easy to remove.
  • Great for all kinds of aquarium.


  • It needs to replace after six months of use because it may prevent the growth of good bacteria.

4) CerMedia MarinePure Bio-Filter Media

It is 1.5-inch sphere bio-filter media made with a kiln-fired ceramic product that contains silicon and aluminum oxide. It comes with a large porous flow-through structure that enables good bacteria to thrive. It has a rough surface, and the filters help to reduce nitrate and ammonia, thereby reducing the level of nitrate in both saltwater and freshwater aquariums.

You can use the product in sumps, canister filters, or wet/dry filters, but the ideal way of using it is in a contact chamber or a canister filter.
The CarMedia MarinePure is to remove nitrite and ammonia under high flow, and deep pore structure gives room for the improvement of low oxygen areas that help control the nitrates. It is with inert ceramic that will not release anything in the water or change the pH.

Reef aquarists will much appreciate the nitrate-reducing function of this filter media. However, this biofilter media is not ideal for planted aquariums since they reduce the nitrate via plant growth.


  • Made with strong ceramic to prevent it from breaking down.
  • Large surface area for healthy bacteria.
  • Increases cycle to get water parameters quickly.
  • Excellent for aquariums that need nitrate reduction.
  • Open pores to enable the easy flow of water through the media.


  • Very expensive
  • The ceramic is not strong enough to stay unbroken after prolonged use.
  • The product can break during the process of shipping.
  • Large spheres that take up space than most media.

5) Govine Bio-Balls

These are multi-textural balls with multiple colors and enclosed in a mesh zippered bag. A kit of this bio-ball contains 500 grams of balls that help promote the exchange of healthy gas and elevate dissolved oxygen levels.


  • It comes with both biological columns and bio balls.
  • The 500 grams package is quite affordable and ideal for many large aquariums.
  • It comes with a mesh bag with a zip.


  • It can change your water chemistry.
  • The materials used are inferior and can be contaminated.

6) Aquatic Experts Bio Balls Filter Media

These bio balls filter are spherical with lots of little spines created to increase each filter’s surface area by two square feet.

Aquatic Experts Bio Balls media is in a black mesh bag, and it is ideal for both salt water and fresh water tanks. The beautiful thing about this product is that it comes with three months money-back guarantee.


  • Easy storage as a result of the mesh bag.
  • Optimized square footage for the colonization of healthy bacteria
  • It helps in the removal of ammonia, nitrate, and nitrite.


  • Larger ponds may require more than one bag.

Buyer’s Guide: How Does Biological / Bio-Filter Media Work?

Fish waste and leftover foods lead to the formation of waste products like nitrate, ammonia, and nitrite. When these waste products are too much, they breed a toxic and stressful environment for aquatic life forms. Sluggish movement, poor appetite, and death are known harmful effects of poor water quality.

When the first bacteria converts ammonia into nitrite, it becomes harmful for aquatic life, while the other type of bacteria then converts nitrite to nitrate, which is not detrimental. This bacteria, known as nitrifying bacteria, derive its energy sources from nitrite and ammonia. It then converts this into nitrate after using it as its fuel.

The mechanical pump helps to provide the required oxygen needed during decomposition when air passes through the biofilter media.

The third bacteria then changes the nitrate to nitrogen gas through a process known as denitrification. Denitrification is a bacteria-driven process that is very vital to reef aquarists because they love corals.

Reasons People Choose Bio-Filter Media Over Other Media

One of the natural ways of cleaning the water in your aquarium is the biological media. Many people prefer this method because it is less harmful and keeps the nitrite and ammonia levels to the barest minimum.

Mechanical media can be harmful as fishes can get trapped inside. Chemical media does not pose any harm, but the chemicals can cause allergic reactions to your fish.

These reasons are why many people prefer the biological media. Keeping your biofilter media in a clean place at all times is very important.

Using a prefilter media should help prevent the accumulated biomass solids from penetrating the media chamber as this will create non-nitrifying bacteria.

When this happens, the non-nitrifying bacteria will overshadow the nitrifying bacteria. While cleaning the prefilter, you should place the media in a position that doesn’t disturb the biofilter media.


Choosing the best media is entirely up to you, but the most crucial point to note is that putting a bio-filter in place is vital as all the nitrates and ammonia in your water will be removed by the bio-media. It could be a threat to the life of your fish.

Other factors to consider are the amount of space in your aquarium’s filter system and the bio-media cost. You should also consider your needs and choose the best aquarium that will suit them.

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