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Filter Media

Filter Media
Filters are essential for the health of your aquarium. They keep the nitrogen cycle going and help keep your tank inhabitants healthy. Filter media is anything placed in a filter that changes the quality of water flowing through it. With the variety of medias available, specific types can be chosen to create the optimum environment in your aquarium.

The three types of filter media are:

  1. Mechanical
  2. Biological
  3. Chemical

All three types are recommended, but an aquarium needs to have biological and mechanical filters at minimum. Components of these media types can be incorporated in the same filter. The three types of filtration utilize three different types of media to perform their functions. This article will help you weave through the maze of terminology and differences between the media that filters use.

About mechanical media
The components of mechanical media are inert - this means that the material this media is made of will do nothing to interfere with your water chemistry. This media mechanically or physically strains solids from water passing through it, which is vital for the efficiency of your biological media. It simply needs to be cleaned - replacement is only required when it can no longer release all the dirt that it holds.

Mechanical media is available in many different porosities, which control the size of the particulate that you can extract. The larger the pores in the mechanical media, the larger the particulate matter must be in order for the filter to extract it. This media, known as coarse media, is easier to clean and reuse than finer media. The pores in the finest mechanical media strain out particles as tiny as one micron, which is 1/90 the diameter of a human hair! The finest media will clarify the tank, but will clog very quickly, and may not be reusable.

Mechanical filtration removes unsightly particles from the tank. This may include fish excrement, sludge, uneaten food, or dust. Aquarium water is passed through a mechanical filter, and the particles are strained out. To prevent build-up, the filter media must be cleaned regularly.

Media What Grade Usage
Fluval prefilter media Very coarse Catches large debris so that small media doesn't need to be cleaned as often.
Blue bonded
Filter pads
, or foam blocks
Coarse to medium Cleans most visible debris.
Filter floss Fine Filters out fine particles providing crystal clear water.
Micron filter pads Extra Fine Removes extra small particulate, even parasites and bacteria.

About biological media
Biological media is anything inert that provides housing for beneficial bacteria that break down dissolved solids to a less toxic form. This is a media that should not be replaced unless it has become too clogged to function.

To understand this media, first we must understand how bacteria thrive:

  • Environment above 55°F
  • Need ammonia or nitrite as food source
  • Need oxygen for life

Bacteria extract oxygen from water moving by them. When particulate matter gets into the media, decreasing water flow, it "starves" that area of oxygen and food, causing bacteria to die in that area. This is why mechanical media is suggested before bio media.

When the bio load increases, the abundance of ammonia and nitrite causes the bacteria to reproduce. Bacteria that consume ammonia reproduce quickly, until the ammonia level drops to zero. Sometimes, they over-produce and cause a "bacteria bloom" that looks similar to smoke in the aquarium. Once the correct amount of bacteria have grown to overcome the ammonia spike, the excess bacteria starve and die, and the "smoke" disappears.

In an established tank, a bacteria bloom is less likely to happen and any ammonia spikes may be gone in 24 hours - often before you even have time to test for it. In new tanks, the time the ammonia takes to be converted by bacteria depends on the amount of fish load and bacteria you start with.

Biological media houses the natural bacterial process involved in the nitrogen cycle. It provides a larger surface area for beneficial bacteria to colonize, where water can pass through the colonies, bringing nutrients and oxygen required for the nitrogen cycle.
A good source of bacteria is a scoop of surface gravel from an established healthy aquarium or some bio media from the filter, as long as the aquarium hasn't been treated with medications or other chemicals. Another choice is a bacteria additive.

Once the bacteria have become established in the biological media, they are difficult to destroy, except by over-cleaning, using chlorinated water, or using certain medications.

As the ammonia-eating bacteria consume ammonia, they give off nitrite, and then in come the nitrite-eating bacteria. These bacteria are slower to reproduce, preferring to wait until ammonia levels are zero.

A variety of media is available for housing bacteria. Small biological media, such as Bio-Glass and Matrix, are extremely porous and boast incredible surface areas. They can accommodate a lot of bacteria in a small space. They also can get clogged easily and lose their effectiveness quickly if inadequate mechanical filtration is used. Smaller media last 2-4 years, and are an excellent option if you have a limited amount of space in your filter. Plastic media, such as Coralife Bio-Balls, do not have the extensive surface area, but they are unlikely to clog and never need replacing.

It is easy to see why aquarists insist on a minimum of biological and mechanical media for filtration. They work in harmony and help keep a healthy, balanced and reliable ecosystem.

About chemical media
Chemical media such as Poly Filter, are effective at removing a variety of impurities, such as copper, chlorine, dissolved proteins, medications, or tap water impurities by binding these unwanted materials and trapping them within the media.

Activated carbon, resins, and other adsorbent chemical media bind and remove dissolved particulates from the water column through the process of adsorption. The two most popular forms of chemical media are activated carbon and resins. Protein skimmers, and ozonizers, are two other forms of chemical filtration.

Activated Carbon
Carbon is filled with microscopic pores that cause certain organic or inorganic materials to stick to them. New carbon works more efficiently than older carbon. When all of the pores are filled, the carbon is no longer effective.

Carbon removes many harmful elements from your aquarium, such as copper, chlorine, dissolved proteins, and carbohydrates. It also removes sulfa drugs and antibiotics, so it should be removed when the aquarium is being medicated, then replaced when treatment is completed to remove any leftover medications. Activated carbon can make your aquarium look crystal clear by removing discolorants, you'll question whether water is still in it.

Ion exchange resins
These filter media are less utilized than carbon, but are becoming more common. These work by attracting a specific molecule to adhere to them. Some attract ammonia or nitrate, and some remove dissolved organics. Ion exchange resins are also utilized in some carbon mixtures like Chemi-Pure and Bio Chem Zorb. The resins often strengthen the filtering ability of the carbon, as well as help biological activity by removing pollutants before they enter the nitrogen cycle. Used properly, chemical filtration can be one of the most useful tools of the aquarist.


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