Biological Filtration in Aquariums: Biofiltration Technology

Will the extra bio-filtration provide any additional benefit for my aquarium?
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The most important type of filtration in any aquarium is biological filtration. Put simply, this wonderful process converts the waste products of the reef inhabitants to a non-toxic state. This complex yet crucial process is carried out by various types of bacteria that live on every surface of your aquarium. In order to maximize the growth potential of the bacteria, aquarists utilize biological filters.
Biological filtration is essential and needs to be adequately established in every aquarium.
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Probably the most commonly used type of chemical filtration in freshwater aquariums is activated carbon. Activated carbon absorbs noxious chemicals and dyes from the water keeping the water clear. Ammonia absorbing media is also found on the market, but is utilized less frequently due to the more efficient removal of ammonia that can be accomplished by a healthy biological filter. Chemical filter media requires replacement over time as it reaches it's absorption capacity. Typically every 4-6 weeks, depending on the filter size, water chemistry, and the stocking density of the pond. Follow the manufacturer's recommendations when using these products. Blok, J. 1986. Biological filtration for the marine aquarium. FAMA9,10,11,12/86.
Photo provided by FlickrGreco, Frank. 1988. The role of biological filtration in closedsystem aquaria. FAMA 8,9/88.
Photo provided by FlickrJenno, Anthony J. 1976. Biological filtration, Pts 1-3, MarineAquarist 7:6, 7,8, 76.
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There are many types of biological filters on the market. Under gravel filters, bio-wheels, wet/dry or trickle filters all have the same goal, to house and grow nitrifying bacteria. These types of filters are essential for fish only systems. Without sufficient surface area for the bacteria to grow, the carrying capacity (i.e. the amount of animals the aquarium can safely support) quickly becomes very low. The reason for this is the presence of toxic ammonia.Conveniently, when we fill our aquariums with live rock and sand, we get a perfect home for lots of bacteria, both nitrifying and denitrifying. All of the surfaces in your reef effectively become your biological filter. The oxygenated surfaces, such as the outer surfaces of rock and top layer of sand, support the nitrifying bacteria. The innermost layers of rock and lower levels of sand can support the denitrifying bacteria. Therefore, there is no need for additional bio-filtration (bio-balls, wheels, etc.) The establishment of the biological filter takes place the moment you place live rock and live sand into the aquarium.For10 years now as biological filtration has dominated the hobby, theusage and understanding of mechanical filtration has plummeted. This may not be a bad thing, but it may generate a false sense ofsecurity as aquariums continue to build their organic loads and reach amaximum capacity.
This hang on power filter utilizes rotating biological contactors (aka bio- wheels). Although this type of filtration works well for fish only aquariums, it is redundant on a reef aquarium.The length of time that the reef’s biological filter takes to establish will vary from tank to tank. If the live rock or sand has just come from the ocean, then it is referred to as uncured. There are many organisms on the rock (sponges, tunicates, crabs, etc.) that will die off as a result of shipping. Therefore the rock needs to be placed into a vat or fishless aquarium to “cure.” Through the use of filtration and water changes, the die off ends and all of the forms of life, including bacteria, start to grow.This is the newly found and booming area of reef aquariafiltration. For over a decade now thishas been the rage. The addition of liverock to salt water fish tanks may have been the greatest trend to ever hit thehobby. The basic principle withbiological filtration is to take waste particles and break them down by safelyby biological means. I guess you couldsay the idea is to break them down where they won’t cause problems, but I preferto think of it in another way. Myvision of this is to add more animals to the ecosystem which use these “wasteproducts” as a food source. Much likeone man’s garbage is another man’s treasure type of philosophy. Explaining this to a new hobbyist is oftendifficult. Try telling someone thattheir tank is polluted and really needs more bugs and bacteria to make itbetter.