| Introduction | | | | through their lives. Ammonia can be deadly, even |
| Filtration is vital for fish to survive in the captive | | | | in small concentrations. It is produced by almost all |
| environment of an aquarium. Aquariums are | | | | life as a by-product of breathing and digestion. In |
| artificial biotopes that rely entirely on the aquarist | | | | addition, decay processes by bacteria in the |
| to survive. Everything that is put into the system | | | | system, reduces excess food or other organic |
| and removed is under the direct control of the | | | | wastes to more base components. One of these |
| aquarist. One of the most important tasks for | | | | is the release of ammonia into the water column. |
| long term success is to control and remove the | | | | Fortunately, nature provides a variety of invisible |
| various toxic wastes that can build up and often | | | | "friends" for the aquarist. These are able to help |
| kill the inhabitants. | | | | control and finally reduce ammonia into less toxic |
| Filtration is the function that removes and | | | | compounds. These are bacteria, often referred to |
| detoxifies the assorted wastes produced within | | | | as beneficial bacteria. Some strains use ammonia |
| the ecosystem. Proper filtration, and a rational | | | | found in the environment and reduce it to a |
| input of food, is vital to the success for the | | | | compound called nitrite. Others take the resulting |
| beginning aquarium, but it takes time to establish | | | | nitrite and reduce it further to nitrate as they |
| appropriate levels of filtration. The novice aquarist | | | | exploit chemical processes to that change as an |
| should understand what filtration is, and how it can | | | | energy source for their populations. Ammonia is |
| be accomplished. Often the filter is provided in the | | | | reduced to nitrite by nitrosomonas sp. bacteria, |
| starter kit, with little explanation of how it | | | | while the resultant nitrite is further reduced to |
| performs. Understanding what is actually going on | | | | nitrate by nitrobacter sp. bacteria. |
| in that media chamber allows an informed choice | | | | The true aim of biological filtration is to promote |
| when adding complimentary filters to strengthen | | | | effective removal of ammonia and nitrite through |
| the purification process. | | | | a natural process called the Nitrogen Cycle. Proper |
| This is not a discussion of the actual filtration | | | | biological filtration offers ideal conditions for |
| equipment types available or a discussion of | | | | nitrosomonas and nitrobacter populations to grow |
| brands and features. That is not in the scope of | | | | and thrive. In the past, most aquariums |
| this article. The actual filter styles will be covered | | | | accomplished this feat by the use of Undergravel |
| in greater depth in a subsequent discussion. Rather | | | | Filters with either an air pump or Power Head |
| it is an explanation of the types of filtration that | | | | forcing water to move through the gravel |
| an aquarium filter must provide to be an effective | | | | substrate in the aquarium. Nowadays, the |
| component of the aquarium pufification process. | | | | Undergravel filter has fallen out of favour, and is |
| I view filtration as divided into three separate | | | | normally replaced with a canister style filter and |
| functions. | | | | media that is very friendly to promoting powerful |
| - Mechanical Filtration | | | | bacterial colonies. |
| - Biological Filtration | | | | Most filters have some component of biological |
| - Chemical Filtration | | | | filtration in them. All you need for the bacteria is a |
| Mechanical, biological and chemical processes | | | | steady flow of water and a clean hard surface |
| perform different jobs, although occasionally they | | | | for the lithotrophic bacteria to attach themselves. |
| will blur the lines of a strict definition. Each | | | | Many of the media in modern filters will meet this |
| identifies and specializes on a different aspect of | | | | minimal requirement, no matter what their other |
| the pollution problem and uses different methods | | | | overall strengths may be. |
| to perform the job adequately. | | | | Chemical Filtration |
| Mechanical filtration | | | | Chemical filtration refers to actively changing the |
| Mechanical Filtration refers to the active removal | | | | characteristics of the water itself. |
| of solid particulate waste from the aquarium by | | | | Besides waste particles and dissolved toxins in the |
| passing a stream of water through a straining | | | | water, the actual characteristics of the water, pH, |
| filter material of some sort. The filter material | | | | hardness and even dissolved metals, can be |
| that can be safely used is wide and varied. The | | | | altered with assorted chemical and resin |
| important concept is the removal of suspended | | | | substances. Unlike the above two filtration |
| solids from the tank and then collecting them | | | | methods, chemical filtration is almost always used |
| somewhere that they can be conveniently | | | | in a filter best suited to mechanical filtration. There |
| removed. The media must then be cleaned or | | | | are a number of filter media that actively change |
| exchanged. Mechanical filter media must be | | | | the characteristics of the water as it passes by. |
| maintained on a regular basis. This requires either | | | | Ammonia removers using Zeolite adsorb and |
| rinsing to remove trapped dirt or actually replaced. | | | | chemically neutralize ammonia. Peat, in all its |
| Because the media is a strainer, it will reach a | | | | assorted types, softens and acidifies water |
| point where it either blocks the stream or fills up | | | | without necessarily removing any particulate |
| and the water flow bypasses it. Most common | | | | waste. There is a long list of other products which |
| filter media used for mechanical filters must be | | | | bond heavy metal ions and remove them, change |
| removed and replaced after it fills up with the | | | | the carbonate content or actively buffer water to |
| debris it has strained from the passing water flow. | | | | a proper pH for a particular species' particular |
| Nowadays, the most common mechanical filter is | | | | requirements. In addition there are products that |
| the outside power filter. In its present form, | | | | remove phosphate and nitrate chemically, usually |
| water is drawn from the tank into the input | | | | with a resin of some sort. The only thing these |
| siphon, forced through the impeller chamber and | | | | disparate materials have in common is that they |
| then must pass through the filter media which | | | | actively change the characteristics of the water. |
| creates a strainer of various sizes to physically | | | | How they do it are as varied as the products |
| remove the particles from the water flow. | | | | themselves. |
| Cartridges, which are simply discarded and | | | | Chemical filtration, when actively applied is the field |
| replaced, are quite popular with many aquarists. I | | | | for advanced aquarists, in most cases. But there |
| personally prefer a design with maximum filter | | | | are many cases where my definition of chemical |
| material blocking the water pathways where the | | | | filtration includes the beginning aquarist as well. |
| water must pass. Cartridge style filters often | | | | Every time new tap water is conditioned, chlorine |
| sacrifice maximum filter material for ease and | | | | or chloramine is removed. Depending on the actual |
| convenience. For this reason, the AquaClear | | | | product, heavy metals may be neutralized in the |
| power filters are my choice. Their use of the full | | | | process of making the water characteristics safe |
| chamber to house assorted media types makes | | | | for fish. Common filtration media, such as carbon |
| more efficient use of the available filter area and | | | | also adsorb certain toxins and dyes removing |
| the water flow through it. | | | | them from the actual water composition. |
| Biological Filtration | | | | Even the newest aquarist is using all the various |
| The removal of organically produced nitrogenous | | | | types of filtration from the very beginning, |
| toxins dissolved in the water column is the main | | | | whether they realize it or not. So understanding |
| aim of biological filtration. Generally, there are only | | | | what these types are and exploiting them to the |
| two toxins that are eliminated when biological | | | | tropical fishes' advantage is vital in success in the |
| filtration is active. Ammonia and nitrite are | | | | first aquarium. |
| produced by the aquarium inhabitants as they go | | | | |