Aquatics Staff, Drs. Foster & Smith, Inc.
Choosing the correct filtration system for your aquarium is an important decision that will impact not only the type and quantity of livestock that you wish to keep, but also the amount of maintenance that the system will require. The filtration system is responsible for keeping the water clear and free of particulate matter (tiny fragments of plant material, leftover food, feces, waste products from the fish, etc.) and toxic compounds that are dangerous to the inhabitants. In this article, I will explain the strengths and weaknesses of the commonly available types of filtration, so you can make the right decision in choosing the filtration for your aquarium.
The three categories of filtration
There are three types of filtration that are necessary for the health of any aquarium:
- Mechanical
- Chemical
- Biological
Before choosing a filtration system, it is important to understand all three, and how they will benefit your aquarium.
Mechanical
Mechanical filtration is the process in which particulate matter is removed from the water. To accomplish this, the aquarium water is forced through a media (material) that is designed to catch and hold these tiny particles. This media is available in many forms including different types of foam, filter floss, pads, micron paper pleats, and diatomaceous earth. To function properly, it is important that this media is cleaned regularly to remove the particulate matter it has trapped, prior to the material decaying and adding to the waste products in the aquarium.
It is a common misconception with many aquarists that by oversizing the mechanical filter, more fish can be kept in the system, and the filter will require less maintenance. All mechanical filters over time will become clogged with particulate matter. When this occurs, it will cause the water flow to either decrease, or flow around the material instead of through it. At that point, the hobbyist should recognize the need to clean the filter. By oversizing the mechanical filter, it may be months before the filter loses its efficiency, which means that it will be months between cleanings. Even though the aquarium may look clean and free of particulate matter, the filter will be holding large amounts of detritus (tiny pieces of decomposing plant or animal material) and other debris that is slowly decaying and contaminating the water with toxic breakdown products such as ammonia, nitrites, and ultimately nitrates. These waste products, therefore, actually reduce the number of aquarium inhabitants that can be housed safely.
Chemical
Chemical filtration removes toxic or unwanted chemicals as the water passes through a chemical media or resin. There have been a number of advancements in the past years, giving us new products that are targeted at removing specific chemicals or excess nutrients from the water. If used correctly, these medias can be incorporated into the filtration to both improve water quality, and reduce the amount of maintenance and water changes needed to sustain a healthy aquarium. Most of these medias do have side effects that need to be addressed when using them. It is important to carefully monitor the water chemistry and perform water changes as necessary.
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