A Quick Guide to Filtration

There are three types of filtration: biological, mechanical and chemical.

1. Biological filtration decomposes the toxic ammonia that fish produce as waste products. All fish tanks need to have biological filtration. It is by far the least inexpensive and efficient way to get rid of Ammonia and other dangerous chemicals in the aquarium. For more information on the Nitrogen Process click here.

2. Mechanical filtration is useful because it filters large particles such as uneaten food, plant detritus etc. If these particles are not removed then they will eventually break down and cause a build up of ammonia.

3. Chemical filtration can remove such substances as ammonia, heavy metals, dissolved organics, etc. Chemical filtration is mostly useful for dealing with short-term problems, such as removing medications after they´e served their purpose, or purifying tap water before it goes into a tank. A healthy tank shouldn't require the use of chemical filters such as activated carbon.

Typical filters perform one to all of the three filtration types. Usually it is Mechanical filtration followed by Biological and finally Chemical if present in the form of activated carbon. Chemical filtration seems to vary by aquarium user as to it's importance. It can be used temporarily to remove Ammonia as well as fish medications after they are no longer useful in the water. It also can adversely affect trace elements need in the water for plants and corals. It is best to ask for advice from you local Aquarium store for your specific tanks needs.

Filters are not maintenance-free. For example, if debris is allowed to accumulate in a mechanical filter, it decomposes into ammonia, negating its primary purpose. Likewise, a biological filter´s effectiveness diminishes as it becomes clogged. Biological filtration requires water movement across a large surface area on which bacteria have attached (e.g., floss or gravel). The less surface area available, the less effective the filter. UGFs are cleaned by regularly vacuuming the gravel. Canister and power filters are cleaned by removing the media and gently squeezing it in a bucket of used tank water (tap water may be used assuming it does not contain bacteria-killing chlorine.

There is no magic formula for what size filter one needs. Again consult your local aquarium store for recommendations as well as looking at the manufacturers ratings. Just like when purchasing a pump it is best not to get a filter that is good for the size of your tank or less. Always be conservative in your estimates to ensure that the tank won't outgrow the filter.