Freshwater Aquarium Filters - Choose The Best One For You
Why do you need an aquarium filter?
An ecological balance is achieved by freshwater lakes and ponds because they are on the large side. Meaning that the size of the fish population adjusts to conditions and the waste is all dealt with biologically there being no build up of ammonia, nitrites or nitrates.
Fish tanks are too small to reach a balance without help. The fish would soon die poisoned by foul water without exernal intervention. The main reason is because we all like to fill our tanks with a density of fish which far exceeds that found in the natural world. The waste produced by fish in this concentration cannot possibly be handled by the resident bacteria and even a weekly change of 1/3 of the water is not going to keep it wholesome. In addition it is imperative that you have a freshwater aquarium filter of some kinf.
How do Freshwater Aquarium Filters work?
A good filter system must be able to work using all three methods, i.e. mechanical, biological and chemical. A fourth way also exists called germicidal or algaecidal, this kind of filtration is usually applied for a particular purpose like getting rid of green water and utilises a UV steriliser.
Mechanical filtration involves using foam and/or fibre to remove large particles like uneaten food and fish waste. Inside the filter the medium is graded from coarse to fine, large particles being removed first by the coarse medium and small particles by the fine.
Biological filtration uses colonies of two types of good bacteria. Fish excreta turns into ammonia which is very poisonous to the fish. Between the two kinds of bacteria ammonia is converted to nitrite and then nitrite is converted to the much less toxic nitrate. Water changes then keep the nitrate levels down to an acceptable level.
Chemical filtration usually uses activated charcoal and/or various specific ion exchange resins. When the tank is first setup chemical filtration is necessary but it is not normally required after that.
The Five Main Types of Aquarium Filters
1.In-Tank filters also called corner or box filters are among the first filter designs. They are considered to be the forerunners of the most modern filters that are used today. They work by pulling water through several different filter media using an air pump. They are cheap but not terribly effective in comparison with other filters that are available. Breeding and hospital tanks are there most common use today.
2. Undergravel filters (UGFs) comprise a grid of plastic pipes with small holes every centimetre or so. The gravel or substrate sits on top of the grid thus creating a water space under the gravel. Water is slowly pulled through the gravel into the filter pipes by up to four ‘air lifts’. The theory is that bacteria will break it down there. The advantages of UGFs are that they are very cheap and easy to setup and run, and the aeration helps keep dissolved oxygen high. They normally do not perform chemical filtration which is one disadvantage. As well as this the small holes in the filter get blocked and waste tends to accumulate because it is not all broken down. Therefore you have to regularly use a siphonic hoover to clean the gravel and 2 or 3 times a year give the filter a thorough clean. This involves scooping out all of the substrate to get at the filter. Undergravel filters, for this reason alone, are becoming less popular.
3. A much better choice are cannister filters. These units comprise a canister with a pump inside and a siphon tube pulling water out of the tank and a return tube to pump the fitered water back in. The typical canister normally contains some type of coarse mechanical media, like ceramic “donuts” or very coarse fibre, some chemical media like filter carbon, some porous glass or stone for biological filtration, and finally some very fine filter fibre. A canister filter therefore performs all three kinds of filtering. Cannister filters do an excellent job keeping the water crystal clear. The downside to these filters is that they tend to be expensive, use expensive media, and need to be maintained every month. They can become nutrient traps if they are not well maintained. This means that all of the fouled filter media actually begins adding nitrogenous waste back into the water instead of removing it. Algae blooms and poor water quality are the result! It is also necessary to add a pump and airstone to aerate the water since cannisters are competely closed. Overall though, when properly maintained, a good canister filter is hard to beat.
4. Power filters simply hang outside and on the top edge of the tank and water is pulled through them with a pump. The water then passes through mechanical, chemical, and biological media in various configurations, then spills back into the aquarium. Aquarists love these filters because they have the advantage of being very efficient, cheaper than cannister filters and are a snip to maintain. Water oxygenation is improved as they are exposed to the air. The oxygen-rich water helps support huge populations of nitrifying bacteria making power filters some of the most efficient biological filters. Particularly good is the biowheel version.
5. Wet/dry or trickle filters. They are only included for completeness. They are essentially used for very large tanks. They are expensive and if they go wrong can empty your tank!
Conclusion
It is essential that you provide efficient filtration in addition to regular water changes to stop a toxin build up which will eventually cause your fish to die. The several choices have been described above. You can now make an informed choice.
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