Overview of Filter Media Types

One of the most important aspects of maintaining a healthy and thriving freshwater aquarium is to have the proper filtration system. Not only are there many different types of filters to choose from, but you also have to think about what type of filter media you want to use. If you are new to the aquarium hobby, you may not realize how much you can customize your aquarium filter. You may be familiar with the three types of filtration – mechanical, chemical and biological – but you may not realize that there are many types of specialty filter media that fall within these categories. If you are serious about keeping your tank healthy and your tank inhabitants happy, take a few minutes to learn the basics about different types of filter media to see if there might be a way to improve the water quality in your tank

Mechanical Filter Media

The purpose of mechanical filter media is to physically trap solid waste particles, thus removing it from the water column. These solid waste particles may include uneaten fish food, fish feces, dust, decaying plant matter, and other organic debris. The most common type of mechanical filter media is a sponge – this type of filter media is very durable and easy to use. Filter wool is also popular and it can trap finer particles than sponge filter media – filter wool is often used to “polish” aquarium water, straining out substances such as mulm and silt. Another type of mechanical filter media is gravel. Gravel is the main source of mechanical filtration in an undergravel filter and it offers the dual benefit of also acting as a biological filter. The problem with this filter media is that it may compact which could inhibit plant growth and may affect water quality in your tank.

Chemical Filter Media

Chemical filter media, or chemically-active filter media, is available in several different forms. One of the most common types of activated carbon (or charcoal) which removes dissolved organic compounds from tank water, thus keeping it clean and clear. The downside of this type of filter media is that if you perform frequent water changes, having activated carbon to remove dissolved wastes from the water becomes unnecessary. Another type of chemical filter media, coral sand, is typically used as a biological filter media in marine tanks but can be used as chemical filter media in freshwater tanks. This type of media can be used in conjunction with an undergravel filter and it serves the benefit of raising the pH and hardness of soft water over time as the sand dissolves.

If you are new to the aquarium hobby, you may not have heard of a specialized type of chemical filter media called ammonia remover. This type of filter media is typically made from zeolite and it naturally absorbs ammonium. The ammonia-removing quality of this type of filter media makes it especially useful in new tanks and hospital tanks which need to be prepared quickly. Another type of unconventional chemical filter media is peat – this substance is often used in biotope tanks to lower pH and to soften aquarium water. The problem with this type of filter media is that it can leech tannins into the tank, turning the water brown or yellow.

Biological Filter Media

The purpose of biological filter media is to provide a surface on which beneficial bacteria can grow and break down dissolved substances in the tank water. Cultivating a healthy colony of these beneficial bacteria in your tank is an important part of maintaining the nitrogen cycle which is the key to keeping your tank water clean and clear. Whereas chemical filter media serves to actively remove substances from tank water, biological filter media simply provides a place for beneficial bacteria to grow. This type of filter media may take the form of ceramic tubes, plastic balls or foam inserts. Ceramic tubes or rings are regarded as one of the best biological filter media options – they offer a finely pitted surface which allows for beneficial bacteria to grow and reproduce. The downside of this type of filter media is that it is rigid and may take up more space than other types of filter media.

Plastic balls, often called bio balls, are another popular form of biological filter media. These balls are covered in tiny pegs which increase the surface area to facilitate bacteria growth while still allowing for uninhibited water flow. This type of filter media is popular in wet/dry filters and they are typically less expensive than ceramic rings. Sponge blocks and inserts serve the dual function of acting as mechanical and biological filter media. Not only will a sponge provide plenty of surface area on which beneficial bacteria can reproduce, but it will also trap solid waste particles.

When it comes to equipping your tank with a high-quality filtration system you need to think about more than just the filter itself. Just as important as the filter model you choose is the type of filter media you fill it with. In order to keep your tank clean and healthy you need to strike a balance in mechanical, chemical and biological filtration and, in order to do so, you need to make an informed decision regarding your filter media.