Of all of the equipment used in an aquarium, none is of more importance than the filter. Although even the most novice of aquarium enthusiasts may be aware of this fact, the wide variety of aquarium filter systems that are available on the market can cause some confusion.
In order to avoid such unnecessary confusion, it is best to first analyze the three primary roles of aquarium filter systems. These are: Mechanical, chemical and biological filtration.
Mechanical Filtration
This type of filtration system is the most basic and easiest to understand. Mechanical filtration simply removes visible particles that are present in the water.
Chemical Filtration
In order to properly understand chemical filtration, it is easiest to view it as the logical extension of mechanical filtration. Whereas, mechanical systems remove the waste that is visible, chemical systems remove the waste that has dissolved into the water and therefore invisible. Chemical filtration normally relies on activated carbon or zeolite to remove the waste.
Biological Filtration
This method of aquarium filtration harnesses the power of beneficial bacteria to propagate the nitrogen cycle in your aquarium in a fashion similar to that found in natural maritime ecosystems. As clarity is essential to understand the fundamentals of this biological filtration, it is important to focus on its basic functionality and not to get lost in overly academic explanations of its performance.
Quite simply, biological filtration systems allow for different types of beneficial bacteria to be present within the aquarium. In turn, some these microorganisms convert the ammonia that comes from the fish waste into nitrites, which in turn are converted by other bacteria into nitrates.
Although nitrates are still harmful to fish in large concentrations, it is easier to monitor and to remove through the simple act of regularly scheduled partial water changes.