The basis of the text of this section is taken, with the permission of the authors, an article from the site (c) Michael Dubinovsky a.k.a Mikluha.
All drawings and photographs in this section (c) Michael Dubinovsky a.k.a Mikluha.
TYPES OF Fish Tank FilterS
Comparative filter characteristics
The table presents the comparative characteristics of filters used in the aquarium. Different types of filters are discussed below.
The table shows that different types of filters are designed for different types of filtering, therefore, the choice of filter should be made by imagining which filtering is most important. If several filters are supposed to be used, they should be chosen to complement each other’s durg. Many modern constructions combine several different types of filters — for example, an external filter may contain, in addition to the usual filler, a bio-wheel, which is of the wet-dry type.
The table below lists some of the comparative filter parameters related to their operation. All this should be taken into account when choosing a filter. If you already have an aquarium, then installing a canister filter can be quite a challenge – pulling the hoses behind the aquarium (this is usually done because they have a not very aesthetic look), installing the filter in the pedestal under the aquarium.
The internal filter is one of the simplest types of filters used in an aquarium. His design has probably not changed since the time of the Tsar-Pea. At least my first filter was exactly like that, using a compressor for lifting water. The principle of operation is clear from the figure. The filler can be any – a sponge (do not use sponges for washing dishes, very often they contain chemicals and do not use cellulose sponges – they will rot), activated carbon, ceramics, etc. In modern constructions, a pump is used to lift water.
Despite its simplicity, this filter can be very effective for a small aquarium, for example, for a quarantine or for launching a new aquarium – it can be transferred from a populated aquarium,
Bottom filter (false, UGF, RUGF)
The bottom filter, called false, UGF (undergravel filter), is a fairly simple design. It is a plastic plate with a large number of holes for the passage of water, placed at a distance of 1-2 cm from the bottom of the aquarium. Ground is put on this plate. Water is pumped out from under the plate using a pump or using a compressor, in the same way as is done in the internal filter. A filler, such as activated carbon, can be inserted into the lifting tube.
As the water passes through the soil layer, the bacteria in the soil and under the plate perform biological filtration, removing toxic ammonia. That’s all the wisdom. To make such a filter is very easy. The plate can be made, for example, from a set of strips in order not to drill a huge number of holes.
If you use air to lift the water in the tube, then you should use wide tubes and small air bubbles. In this case, the filter performance is greater.
The advantage of this filter is its simplicity and efficiency. However, it has several disadvantages. First of all, this filter must be cleaned, like all other filters, and it is more difficult to do. To make life easier, provide a second tube at the opposite end of the aquarium. It must be closed, otherwise the water will be sucked through it, and not through the ground. For cleaning, this tube opens and a hose is inserted there, which starts up falsely. Water is pumped into this hose, which is removed through the second tube. Turning the hose from side to side can effectively clean the space under the false. Additionally, you can make a brush on a flexible handle, like the one with which the water pipes are cleaned. Some branded filters have a protective mesh in the hole in the board where the tube is inserted. You will have to remove this grid, otherwise it will be unrealistic to clean it in this way. For a similar reason, do not put the filler (ceramic, sponge) in the space under the filter. However, if you rework the aquarium every six months, then you can not worry about it.
Another disadvantage of the filter is its poor performance in shallow ground. Do not use fine soil or a thick layer of it with such a filter. Do not use sand that simply falls through the holes in the board. The use of a bottom filter does not eliminate the need for regular soil cleaning with a siphon, quite the contrary. Driving, faster than in the absence of a filter, with mud will lead to the appearance of oxygen-free zones and soil rotting in these places. When soil is clogged, the efficiency of biofiltration is sharply reduced.
A problem may be the “colonization” of the space under the plate by various inhabitants — a pipemaker who got there, snails (I had this in one of the aquariums where large stones were used as soil, cichlids living in this aquarium received a portion of snails as food and As you can see, one of the snails slipped under the plate, the shells of dead snails constantly littered the lifting pump), with some small and mobile fishes that were buried in the ground.
The backflow filter with reverse flow of water (RUGF – reversed undergravel filtration) is supposedly more efficient than the usual bottom, because the water pumped under the plate "lifts" the dirt from the soil. But, again, the primer must be cleaned. For pumping water under the bottom, you can use a special pump, which has a change in the direction of water flow, or connect a tube to the outlets of a conventional pump. At the entrance of the pump is usually placed a mechanical filter – a sponge to retain dirt, which can accumulate under the plate.
You should not use such a filter in a plant aquarium, although some use it. My plants grew well in a tank with a bottom filter, but this required more attention. The problem is that with this filtering, nutrients are leached from the soil (where they are available to the roots of plants) into the water, where they become available to the algae. More about this is written in the section on algae.
In conclusion, we can say that the bottom filter is a very effective filter, but like all other filters, it requires care and understanding of the principles of its operation.
External filter (outside filter)
The picture shows the principle of the canister filter.
If you read about the principles of filtering and the device of the internal filter, then everything should be clear without further explanation. Nothing new, a filler (or several) is placed in a separate container for various types of filtration (mechanical, chemical and bio-filtration, which is the most important). The main advantage of such a filter, compared to, for example, with a bottom filter, is its ease of operation – it is more convenient to clean it. You can hide out of sight (which sometimes results in filter cleaning being postponed to the eternal "tomorrow"), you can change the fillers, depending on the type of filtration you need – for example, put activated carbon for several days to clean the water after using the antibiotic. Water pumping is usually carried out by the pump, although you can adjust the compressor – a similar scheme can be seen in the old books on the aquarium. But, since the efficiency of pumping water by the compressor is low, we will not dwell on this.
Inside are various fillers. Manufacturers recommend putting filtering materials only of their own production, but this is understandable. Feel free to put the fillers of other companies or make them yourself. for example, from pepsi tubes. Usually, something like a leaky basket with several compartments is inserted into the filter canister so that it is convenient to hold different materials without mixing them.
Different manufacturers recommend different order of fillers, you can stick to their order, but you can come up with your own and see what happens. The first is usually a mechanical filter that retains large dirt, It should be cleaned more often. Then you can put activated carbon if you want, or some other chemical filler, for example, zeolite to filter ammonia. Last you can put a sponge for fine water or peat or something else.
Currently, the external filter is perhaps the most popular filter for freshwater aquariums and you will not be difficult to choose among them a huge variety of the one that you enjoy. By power, you need 2-4 volumes of an aquarium per hour. Do not forget that these manufacturers often provide for an empty (or with a new filling) filter and performance depends on many factors, including the position of the filter relative to the water level in the aquarium. The main parameter is convenience – whether the lid opens easily, whether it has a carrying handle (it is inconvenient to haul a jar of water by the hoses) and most importantly – how it runs dry when it is below the aquarium and the water enters it siphon.
External filter – is arranged similarly and represents a box that hangs on the outside wall of the aquarium,
External filters are of various types and designs. Compared with the canister they are very easy to maintain, because they do not require disconnecting hoses, etc.
The disadvantage of them compared to canister is a smaller volume for fillers.
Often, the output of such a filter is set to a bio-wheel, which greatly increases the filter’s capabilities
For small aquariums, they are probably one of the most convenient filters.
When you clean the filter, do not change the entire filler at once – the bacteria will quickly “run across” to the new filler from the old one.
Such a canister filter is very easy to make yourself. All you need is a tank for fillers and a pump that must stand after the filter (so that it is less clogged with dirt).
Sand filter (fluidized bed filter)
This filter is one of the most effective for biological filtration of water, despite the fact that it is not very widespread. Even a small filter can provide effective filtration for a large aquarium. In the filter, water flows from the bottom, constantly mixing sand. Bacteria settle in the sand. Often, the air is supplied to the air from the compressor to saturate it with oxygen. Mixing the sand grains on which bacteria are located provides oxygen and organic matter to the bacteria. At the same time, the grains of sand rub against each other, not allowing the bacteria and organic matter to grow, which reduces the efficiency of the filter.
The disadvantage of this filter is that it does not carry out mechanical and chemical filtration, Moreover, it can be turned on only after the mechanical filter, otherwise it will be clogged with dirt, which will reduce efficiency. For successful operation of the filter, a flow of water is needed, which, on the one hand, will lift all grains of sand, on the other, will not wash them out of the filter. But, debugged once, this filter will work for a long time and efficiently.
Such a filter is also easy to do yourself. It is necessary to adjust the flow of water so that the sand does not leach into the aquarium. Too little flow will cause the sand to settle on the bottom. To simplify the adjustment of water flow, the filter housing is best done transparent. You should regularly check the amount of sand in the filter, pouring if necessary.
The bio-wheel is a wheel with blades that look like a mill. It is either partially immersed in flowing water, or located so that water flows on top of it, setting in motion. The blades of the wheels, which are usually made wide to increase the area, are sown with bacteria that carry out bio-filtration. Due to the fact that part of the time the blades are in the air, the water is saturated with oxygen, necessary for bacteria. Therefore, this filter is one of the most effective for bio-filtration.
As you know, the bio-wheel can not hold large dirt. Usually this wheel is placed at the outlet of a mechanical, external, bottom or other filter that performs mechanical filtration.
New wheel rotates fast enough. As it is colonized by bacteria (from several weeks to a month or two), the wheel starts spinning slowly, sometimes with stops. This is normal – no need to clean the wheel from the bacterial film. Do this only in the case when it stops spinning altogether – try not to remove all the bacterial film so that settling takes place faster.
Another advantage of the wheel is that the water entering the aquarium is saturated with oxygen. On the other hand, if you use CO2 in a plant aquarium, then when using a bio-wheel it will quickly evaporate from the water. However, in a plant aquarium, the use of bio-wheels is hardly advisable, since well-growing plants (and when using CO2 plants usually grow well) themselves perform bio-filtering, using a filter
Here is a filter using a wheel (on the right in the open position)
This wheel is easy to make yourself glued from plastic. It is better to make the blades rough, so that it is easier for the bacteria to "cling."
Wet-Dry and Trickle filters
According to the principle of action, the trickle filter is similar to the bio-wheel described above. The main idea is to contact the filtered water with air to saturate it with oxygen.
In one of the variants of such a filter, the water from the aquarium, before going through the filler, gets on the board with a large number of small holes, is sprayed, saturated with oxygen. At the same time, the efficiency of bio-filtration increases dramatically.
As a filler, special balls or ceramics are used that are large enough to provide air access throughout the entire volume.
This filter is easy to make yourself. It must be remembered that this filter is ineffective for mechanical filtration – removal of large debris.
Protein skimmer, Protein trap, Flotation column
This filter is mainly used in saltwater aquariums, since it is possible to create much smaller air bubbles in salt water than in fresh water. Therefore, its performance increases. This does not mean that it cannot be used in fresh water – if you have a bog full of organic matter, so that when aeration bubbles form on the surface of the water and do not burst for a long time, then you just need to use such a filter. Or rather, start cleaning the aquarium.
The principle of the filter is based on the principle of flotation – when the bubble pops up, the air bubble is capable of “sticking” at the air-water interface, due to the surface tension of water, large molecules, mainly organic. In principle, this filtering method can be attributed to chemical filtration. The meaning of using a skimmer is to remove organic matter from the system before it can decompose. Due to this, it is possible to reduce the load on the biological filter, to reduce the formation of nitrates in the aquarium, which is important when the content of sea corals that die at elevated concentrations of nitrates in the water (you should try to maintain the level of nitrates in such an aquarium less than 10 mg / l). In a freshwater aquarium with fish, a concentration of up to 100 mg / l is quite acceptable if you do not grow fry. The concentration of nitrates is easily reduced by regular water changes. Therefore, the skimmer is considered here very briefly, without a theory that is fairly simple and necessary when choosing a skimmer.
Skimmers are of several types:
- with direct current of water (co-current skimmer)
- counter-current skimmer
- with air supply through a nozzle (venturi-driven skimmer)
To increase the efficiency of the skimmer, it is necessary to increase the contact time of the air bubble with water. Therefore, skimmers with a direct current of water that flows from below and flows upward along with air bubbles are ineffective. Skimmers with a counter-current of water (shown in the figure) are much more efficient, since the contact time is much longer and more turbulence is formed. The air spray gun used in the skimmer should ensure the formation of very small bubbles. A wooden sprayer is usually used, the disadvantage of which is that it must often be dried and cleaned.
A skimmer with an air supply through the nozzles acts like a filter, which sucks air into the outlet tube – by reducing the pressure in the jet of fast-flowing water, according to the Bernoulli principle. Such skimmers have an internal pump and do not require the use of air diffusers.
The foam formed during flotation is collected at the top in a special container, which is regularly emptied. The designs of skimmers are a great variety, distinguished by their usability and efficiency. In principle, there is nothing difficult in the manufacture of a homemade skimmer.
Sometimes ozone is used instead of air to increase the filtration efficiency and sterilize water. When applying it, all precautions described in the section on the ozone filter should be applied.
The disadvantages of the skimmer include the fact that they can remove organic matter from the water too well. Then, for example, plants may lack the nitrates formed during bio-filtration. Fertilizers, especially chelated, can also be removed from the water. Therefore, it does not make sense to use a skimmer in fresh water.
As described in the section on the nitrate cycle in an aquarium, nitrates are the final product of bio-filtration. They are not poisonous (most fish tolerate nitrate concentrations up to 100 mg / l or more), unlike ammonia and nitrite. Over time, they accumulate in the aquarium. One way to reduce their concentration is to regularly change the water in the aquarium. Unfortunately, fish fry and invertebrate organisms, such as corals in a saltwater aquarium, are sensitive to even small concentrations of nitrates in the water (for corals, it is necessary to maintain