The simplest internal filter is an air-lift filter: a compressor-aerator, a lifting tube, a foam sponge, put on the perforated part of the tube, into which air is blown from the compressor through the dispenser. Airlift – a device designed to lift a liquid from a certain depth to a certain height with the help of compressed air. The principle of its operation airlift based on the difference between the specific gravity of water surrounding the riser from the outside, and the specific gravity of the water-air mixture filling the pipe. If air is introduced under sufficient pressure into the lower part of the riser, which is lowered into the water, the air emulsion formed in the pipe (a mixture of water and air bubbles) will rise due to the difference in the specific mass of the emulsion in the pipe and the water in the aquarium.
The design of airlifts can be schematically represented as a vertical or slightly inclined lifting pipe, which is partially submerged in water. At the lower end of the submerged part of the riser, there is a gas distribution device (sprayer) for supplying precompressed air to the riser. The upper end of the riser, called the mouth of the outflow, is connected to a separation device designed to separate the water being raised from the air bubbles. The air supplied to the atomizer, in the form of bubbles, enters the lifting pipe and, under the pressure of buoyancy, rushes to the mouth of the airlift spout. Due to the viscous forces (adhesion forces between water molecules), some amount of water surrounding the bubble takes him upwards. In the event that the air flow is low, the water in the riser will only mix or rise to a certain height. "
Air lift filter – despite its primitiveness, can be quite effective for a small aquarium.
External filters also come in various types and designs. This, above all, the so-called canister filters and filters – "waterfalls".
Canister filter installed outside the aquarium, as a rule, in the cabinet is an excellent means of water purification. Its main purpose is biofiltration. The principle of operation is as follows: the filter must be located below the water level (otherwise it will not work), the water through the suction hose enters the filter, is passed through various types of fillers and returns to the aquarium through the pressure hose.
The disadvantages of canister filters include, first of all, the high cost of the device itself and the fillers and the labor intensity of washing. The use of canister filters is also limited by the need to have free time in the pedestal under or next to the aquarium, which, for example, is not always possible if the aquarium is in a rack.
The canister operates on the next cycle. As long as the beneficial bacteria have not settled the substrate, the filter actually works only as a mechanical one. It gradually becomes polluted, causing the water pressure to drop. But there is a reverse process. Dirt is food for bacteria. They break down the organic matter that accumulates here and is processed into nitrate, i.e. begins biological self-cleaning filter. Full colonization of the substrate by colonies of beneficial bacteria occurs within 2–4 weeks. And then it all depends on what process will take up – pollution or self-cleaning. If the first, the filter will continue to be contaminated. Not as intense as the first two weeks, but inevitably, especially if the water intake is not covered by the prefilter. When the filter performance drops below 30% of maximum, it needs to be cleaned and restarted, otherwise “tipping” may occur. If self-cleaning gains the upper hand, the filter on the contrary is gradually freed from dirt and the performance that falls to 50-70% of the maximum is restored. Theoretically, after that the filter should work forever. In practice, productivity is not fully restored, and stagnant zones are still formed inside the canister. Therefore, it is recommended to clean it from time to time, even if the water pressure is strong.
Many aquarists hold the view that since the main purpose of a canister filter is biofiltration, there is no point in overloading this device with mechanical filtration. For this it is better to use an internal filter that is regularly washed.
Compared to canister or, as they are also called, "portable", "waterfall filters" ("mounted") are cheaper and easier to maintain. The disadvantage of them compared with the canister is a smaller amount of filter elements. These filters are more suitable for small aquariums. In our country, they are much smaller distribution than abroad.
Samp – open or, as they say, "irrigated" filter. Devices of this type are common in marine aquarism and less common in cichlid farms. Among the filters of other types, samp is distinguished first of all by its impressive size, which can be close to the size of the served aquarium and even exceed it. The body of such a filter, it is called the collector (the English name is sump), is usually located under the aquarium in the pedestal or on the lower tier of the rack. The collector consists of two parts, separated by an airtight partition that does not reach the top edge: a tank of a constant level, where the water comes from the aquarium, and a tank of variable level, where the return pump is located, pumping the purified water back into the aquarium. .
The design of the sump for a cichlid aquarium is simpler and does not require the use of complex and expensive equipment that is part of the marine sump. An example of a samp serving a 1200-liter aquarium with Tanganyik cichlids is shown in the photo below. The filter is divided into four compartments filled with various substrates.
The irrigated filter simulates the processes occurring in the surf zone, when the waves roll on the shore and the water mixes with air, being saturated with oxygen. On the shore, the wave, seeping through the layer of sand, weakens, and the water flows back into the reservoir. The irrigated filter operates according to the same principles. The water in this filter is sprayed over the filtering material, that is, it irrigates it, and, mixing with air, it is intensely saturated with oxygen. This leads to the fact that aerobic processes occur efficiently, and ammonia-oxidizing and nitrite-oxidizing bacteria well purify water from toxic nitrogens. The advantage of sampons is significantly greater efficiency in maintaining biological balance in the aquarium. The disadvantage is that they take up a lot of space and require from the aquarist more qualifications and careful attitude than the canister ones. There are also designs of collectors located above the aquarium. Then the water level in the case of an open filter remains constant and is set by the system of water overflow into the aquarium. A pump that pumps water into the filter is placed in the aquarium. For large sampons, this scheme is less reliable and convenient, although workable, but it is successfully used for small-sized aquariums that have a filter built into the cover (in particular, Aquael and Jebo).
A kind of sump can be considered as open water treatment systems of large aquarium farms, in which the filter mechanical and biological treatment are separated. In particular, in the discussion of the "C.K.AT." implemented the following design of irrigated filter (above in the photos). Each of these filters serves a rack with several aquariums. Of these, water flows by gravity through a pipe that unites the drains of all aquariums, into the mechanical filtration unit – first on a stainless steel sieve, where large particles of suspension remain, then through a thin layer of foam rubber flows into the chamber filled with ceramic cylinders. Pump performance provides pumping from 1.5 to 2 volumes of water in all aquariums per hour. The sieve is cleaned during each feeding, the foam rubber is washed every 5–6 days, and the ceramics – approximately once a month. The biological treatment unit is a column of 8–9 cassettes filled with porous material with holes in the bottom for free flow of water. The cassettes are mounted one on top of the other with a small air gap so that the lower one is above the level of the filter tank. A separate pump with a capacity of 600–1200 l / hr water flows into the upper cassette and flows downward sequentially through all lower cassettes. For the most efficient use of the substrate, water is supplied through the sprinkler, evenly distributed over the surface of the filler. After passing through all the stages of purification, water is pumped into the aquariums.
Is it possible and necessary to turn off the external filter during feeding of fish and during water changes? Not. It is better that he worked continuously. Firstly, it will last longer, since the greatest load on the mechanisms and the electrician is at the time of start-up (remember the light bulbs, which often burn out just when the light is turned on). Secondly, there is a risk that an aquarist, distracted by something, will forget to turn the filter back on after the procedure is completed, and the latter will stay disconnected for a long time. Therefore, the water intake should be placed in the lower half of the aquarium, so that when pumping 25–50% of the volume of water when it is changed, the filter remains operational. And even more so in no case can you turn off the filter for a long time: at night, at the time of departure, etc., and if this happened for some reason, it is recommended to wash the fillers and restart the filter. As previously noted, for a heavily polluted filter, even 2-3 hours of inactivity can harm the inhabitants of the aquarium.
Filters external filters. Most often, the organization of filtration of a cichlid aquarium is such that the external filter works mainly or entirely for biological treatment, and therefore should work without cleaning for a long time. Therefore, it makes sense to wash it only when an objective need arises, manifested, for example, in a significant decrease in the performance of the pump (water pressure) or the detection of other signs that the filter has stopped working properly. If we talk about some conditional terms, then you can try to make the first cleaning six months after the start of the filter. At the same time, to assess the degree of contamination of the fillers, it is possible to make changes in their composition and interposition. And, perhaps, you will find that there is almost no dirt in the fillers, and your intervention was not required. After that, you can re-connect the filter and forget about its existence for quite a long time. By the way, the dark brown mass on the filter elements is not dirt, it is those very useful bacteria.
But at some point, the time for routine maintenance will still come. How to wash? As a general principle, with respect to half of the filter elements, you should limit yourself to surface treatment using aquarium or distilled water in order to wash off large dirt, but keep bacteria colonies, and wash the other half completely with warm tap water. Moreover, if the filter is loaded with sponges, then it makes sense to thoroughly wash the lower most polluted sponges and, when restarting the filter, change their positions with sponges previously located at the top. Naturally, this is not an axiom. If you, having opened the canister, have found out that the filter is not very dirty, you may not bother with thorough washing of the fillers or even not at all washing them. Conversely, for example, if you restart the filter after “tipping”, all filter elements must be thoroughly re-washed.
Now specifically about the various types of fillers. Experience shows that it is better to wash the sponges under running water, rather than rinsing them into the pelvis, while draining and changing the water several times, although large-pore sponges used for canister filters are quite good at washing and right under the faucet.
Porous material can not be washed clean. If its smallest pores are clogged, and the biosubstrate stopped working well, then it can only be replaced.
Ceramic rings that play the role of a filtering element for mechanical cleaning should be washed with clean water. This is quite easily done with a colander and a watering can. However, if the filter is filled in whole or in large part with ringlets, then part of them should be subjected to gentle treatment in order to preserve the bacteria, or even not to wash at all. The same can be said about the so-called "bio-gifts".
Activated carbon, zeolite, and carbon sponge are consumables that must be replaced after mining.
And finally, a padding (fine filter). According to the manufacturer’s recommendations, the padding is also a consumable item and should be replaced with a new one when it is polluted.
Contaminated padding may cause filter malfunction and water turbidity in the aquarium. Therefore, there are recommendations of experts to periodically open the filter and replace the padding polyester in it, without waiting for a general restart. This, however, is not necessary if the filter already works normally.
Internal filter sponges. There is a dilemma: on the one hand, if the filtering elements are too thoroughly cleaned, not only dirt, but also beneficial bacteria are eliminated on them, especially if you use chlorinated tap water, especially hot water; On the other hand, poorly washed filter elements can cause a violation of the filter’s washability, the formation of stagnant zones, water turbidity and even the production and release of poisonous substances into the aquarium. Well, even if nothing terrible happens, it is more convenient and practical to wash water from under the tap.
In the original instructions, as a rule, there is a prescription to wash the sponges of internal filters with aquarium (dechlorinated) water at room temperature. Should I always follow the instructions? In my opinion, more often than not. But first, you need to understand for yourself what tasks the filter performs and act on this basis.
Equipment classic cichlid aquarium involves the simultaneous presence of external and internal filters, of which the first works on biology, and the second on the mechanics. In this situation, there is no point in preserving the beneficial bacteria in the filter element of the internal filter, and the more often and carefully you wash it, the more hygienic it is. According to the averaged rule, the sponge of the mechanical filter should be washed once a week, but this rule is only indicative and strongly depends on the density of fish landing and pump power. Some internal filters due to contamination of the sponge and impeller quickly lose their productivity, and you have no choice but to wash them regularly. Other models can work for months without cleaning. But despite this, do not be lazy to wash the filter element. A large accumulation of dirt in the filter can cause hexamytosis and bacterial diseases of fish.
Now let’s move on from the cichlid aquarium to the usual decorative one – with a thick layer of soil and a large number of living plants, in which only an internal dry glass filter of small productivity is present from the filtration equipment. The size of the filter material in this filter is very small. Therefore, to talk about the implementation of their effective biofiltration is not necessary. How does the elimination of poisonous nitrogen in these aquariums? Very simple. Beneficial bacteria can live not only in the biofilter, but also in the soil. And besides, the plants themselves are powerful absorbers of ammonia, nitrite and nitrate. Recall, because in the vast majority of aquariums of the Soviet era there were no filters at all. Using small glass filters makes little difference. In fact, these filters work only to create water flow and mechanical filtration. Therefore, the owners of such aquariums should not be fooled by the illusion of the biofilter. Accordingly, it is advisable to clean the filter elements regularly and cleanly, as is the case with the mechanical filter of the cichlidarium.
It is a very bad case if there is very little vegetation in the aquarium (or not at all) and only a small glass filter is used – unfortunately, the situation is quite typical for beginning aquarists. Here you should first of all think about upgrading the equipment, and only then about how to properly clean the sponge, because even if the system functions somehow with this filtering, it is up to the first mistake, overfeeding, etc., because it unstable. The most expeditious solution is to disassemble the glass and replace the regular small sponge with a larger openly located one – if the design allows, or to purchase the replacement of the existing glass filter with a filter head. And then it really makes sense to gently treat the beneficial bacteria living on the filter element.
Further. The fact that large sponges, in order to completely clean off the sludge, in my opinion, should be properly rinsed in the pelvis, rather than rinsed under running water, has already been mentioned above. However, it can be done differently – to unscrew and squeeze the sponge firmly or to beat the dirt out of it, knocking strongly against the wall of the sink or bath, under the tap of running water. Try it, maybe you can do it better. Here it should be added that fine-porous sponges are generally poorly washed out, therefore, as an option, you can not wash them, and each time replace them with new ones. Thus, filter maintenance is simplified as much as possible. Well, about the synthetic winterizer, which is included in the regular set of filter elements of some internal filters, also already mentioned above.
And finally, how to keep good bacteria on the filter element, if it is required to turn off the filter for some time or to transport it. Here we must bear in mind that for the life of nitrifying bacteria not only a substrate is required, but also aerobic, i.e. oxygen-rich environment. If you turn off the biofilter, the current of oxygen-enriched water stops and the bacteria die after a while. The first thing that comes to mind is to put the filter element in a container with water during long maintenance work and to provide aeration with a compressor. However, according to research by Timothy Hovánek, another method based on the wet-dry principle, i.e. storing the wet substrate in the air outside the water. Although, in principle, both methods are acceptable.
One of the trends of modern aquarium – a significant increase in the size of the used aquariums. Fifteen years ago, a 200-liter tank was considered large, now half a ton — this is already quite normal volume. This trend is even more obvious for a long time in foreign cichlid breeding. There are those who disagree, objecting: "If earlier Managuans were successfully kept and bred in hundred liters, then why should they now need several times more displacement?" Here we only note that even if we abstract away from the ideas of a humane attitude towards animals and Western European anthropomorphism, large aquariums have a number of undoubted advantages. And not only that the fish grows in them better and less conflict. Such an aquarium also has a significantly large margin of stability as a biological system. For example, treatment of fish with an antibiotic in an aquarium of a small size most often leads to disruption of the biofilter, whereas for large volumes there is a successful experience of using ciprofloxacin in the general aquarium without significant damage to biological equilibrium. Also longer is the allowed idle time of the biofilter in the off state and the inactivity of the aerator. Although, of course, it depends not only on the size of the aquarium, but also on the density of fish landing. However, it is also obvious that in a larger aquarium it is easier to provide a greater displacement for each fish than in a small aquarium. Accordingly, the water in large aquariums is almost always cleaner, and the fish in them feels better.
Aeration is the process of saturating water with air or oxygen (with parallel displacement of carbon dioxide), which occurs both naturally by gas exchange on its surface and artificially by forced aeration.
Fish breathe the oxygen they take out of the water and exhale carbon dioxide. If there is not enough dissolved oxygen in the water, the fish may suffocate. This condition is called hypoxia. Signs of lack of oxygen: the fish open their mouth, often move the gills, and concentrate near the surface of the water, where the oxygen content is higher.
But aeration in the aquarium is needed not only for fish. Saturation of aquarium water with oxygen is one of the prerequisites for a successful nitrification process.
The most effective and reliable method of aeration is the air supply to the water column by a compressor. A nebulizer is connected to the compressor through an air hose, which serves to spray air into the smallest bubbles – the so-called bubble aeration. Air bubbles constantly take along border water. The result is an upward flow of water. There is a very small difference in velocity between water and bubbles. The bubble moves in a very uniform flow, and the more pronounced the turbulence is, the better the surface layer will be removed on the bubble, which is saturated with oxygen. Water depleted in oxygen is rapidly supplied to the surface of the bubble and enriched with oxygen. It is considered that the aeration is the better, the smaller the size of each of the bubbles.