Filtration Basics

Filtration Basics

If you wish to become a successful aquarium hobbyist and to keep your fish alive and healthy, it will be important that you understand the basics of aquarium filtration. The home aquarium is a "closed system". This means that any wastes produced will remain in the same body of water until some type of filtration removes or neutralizes the wastes. Fortunately for you, the aquarium hobbyist, there are three basic categories of filtration that will enable success with your aquarium.

Mechanical filtration is perhaps the easiest to understand. This is the process of physically removing larger waste particles from the water by trapping them is some type of mechanical device. These devices make use of a filter pad made of floss material or maybe sponge material. While the water flows through these materials, particles are trapped in the matrix of the mechanical media. This will usually result in crystal clear aquarium water with no floating particles. The mechanical filter media will require cleaning or replacement as it becomes clogged with waste particles. This clogging can substantially slow down the flow rate of certain types of filters, so you will need to daily observe the flow rate as a good indicator of when the mechanical media will need to be replaced. You should be aware that the waste material trapped in the mechanical media is not really removed from the aquarium environment, it is just all trapped in a convenient place for you to remove it. For this reason, the more frequently you clean the mechanical media, the better the water quality should be in your aquarium.

A second type of filtration for the aquarium is called chemical filtration. This involves using some type of chemical media to physically remove or neutralize the waste products in your aquarium. Common chemical media include activated carbon, resins or filter pads impregnated with chemical compounds. As the aquarium water passes through these materials, the specific chemical media will attract/bind/remove specific types of chemical wastes. Among chemical media, activated carbon has the broadest range of types of chemical wastes it removes. That, along with its reasonable cost, makes it by far the most popular type of chemical filtration for the aquarium. Resins are man-made and designed to remove specific types of chemical wastes. One advantage to resins is the ability to design some to physically change color when they become exhausted, which means they are totally clogged with chemical wastes and need to be changed/recharged. Rechargeable resins can save you significant amounts of money over their useful life span. With any type of chemical media it is important to have the water flow through a mechanical media first so that larger physical wastes do not clog the surface area of the chemical media. It will be important for you to follow the manufacturer’s recommendations as to how often to replace the chemical media. While chemical media plays an important role in removing waste material in the aquarium that is not even visible to the human eye, it is also excellent at removing discoloring agents like dyes from foods or medications. In fact, many medications will require that you temporarily remove the chemical media while treating the aquarium. Chemical media can also help protect your fish from harmful household products used near your aquarium.

While these first two forms of filtration can result in crystal clear water in the aquarium, without the third, biological filtration, your fish will have little chance of success. Biological filtration is responsible for converting the very toxic ammonia released from the metabolic process of respiration. This ammonia is secreted through the gill membranes and in the fish’s urine. The process of biological filtration involves large populations of beneficial nitrifying bacteria. These bacteria will use the ammonia as a food source and convert it to nitrite, a slightly less toxic compound. If it stopped here, your fish would still be in trouble. Fortunately, Nature provides a second class of nitrifying bacteria that will use the nitrite and convert it into fairly non-toxic nitrate. It is up to you, the hobbyist, to remove nitrates from the aquarium with regular partial water changes. Biological filtration requires three parameters to thrive: a food source (fish’s wastes), oxygen/oxygenated water, and surface area for the bacteria to colonize. The nitrifying bacteria will colonize any type of surface area, but some surfaces are better than others. Recent developments have provided you with many, many choices of biological media to be added to the filter system or placed in the aquarium to provide more than adequate surface area for the nitrifying bacteria to colonize. Once again, it is best to first direct the water flow through a mechanical media before it passes through/over the biological media.

While biological filtration is essential to the health of the fish, also using mechanical filtration and chemical filtration can make your aquarium experience much more rewarding. You can select from a vast selection of filter types to fit any size aquarium and budget. It is difficult to get too large of a filtration system, but it is extremely important to get one that you will maintain properly. If the filter is not properly maintained, it will provide little if any benefit to your aquarium and will be a constant source of irritation. With a little bit of knowledge and planning, you should find it easy to provide all three stages of aquarium filtration and provide a healthy environment for its aquatic inhabitants. Remember that your fish depend on you to maintain the proper environment for their health.