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Anyone who would like to engage in the reproduction of fish, much has to do differently, rather than simply with their content. As will become clear from the following chapters, in most of the large biotopes considered by us as the home of the most popular (as colorful) aquarium fish, water contains extremely few mineral substances. Therefore, the main tasks of preparations for spawning are connected with the "water" area. The current notion that exceptionally soft water is good only for spawning is wrong. Many species of fish and during development show increased demands for rigidity. However, for most fish, it is impossible to accurately identify the limits of rigidity in which the fry can be succeeded or not succeeded. The quality of spawning water is always determined by many factors together, and therefore it is impossible to establish in advance either the necessary rigidity or pH. It is variable, and in soft water it is much more difficult to keep under control than in somewhat more rigid. In addition, we must not forget that the cichlids from the Central African lakes, which have become especially popular in aquaria for the last decades, are accustomed to a relatively high pH and, accordingly, sour water does not do them good. When preparing water for fish farming, the following are the most significant ones:

О Partial or complete desalting of excessively hard water by using ion exchange resins;

О Maintaining the purity of water by filtration through activated charcoal;

O Acidification of spawning water through peat;

О Disinfection of water with ultraviolet rays;

O Ozonation of water.

Partial or complete desalting of too hard water

In many regions of Europe, water is not at all intended for the reproduction of tropical fish: it is too rigid and requires special treatment. I mean desalting or demineralization, and it is possible to undertake such treatment in whole or in part. In partial desalting or decarbonisation, bicarbonates contained in water are removed, while additives that increase hardness and are represented by sulfates, chlorides and the like are removed only after the final complete desalination . Usually, fully demineralized water in aquaria is obtained using a two-column cation-anion desalination apparatus . Such devices are produced, for example, by the company Stein in Duisburg, and in different sizes (the height of the columns is 90, 120 and 170 cm). The device is also supplied with an integrated conductivity meter, and after the consumption of ion exchange resins it is capable of self-regeneration. Another method (in which independent regeneration of reagents is not possible) is called the principle of mixed action. The resins are mixed here, and during the flow of water all dissolved salts, silicic acid and carbonic acid are extracted from it, and recently also nitrates. Such water is extremely pure, and its electrical conductivity is in the range from 1 to 0.1 mg / l. The total content of salts - 0.1 mg / l - corresponds to approximately 0.2 nS , and in fact water "distilled" even at 10-20 nS is most often considered quite suitable.

In cassettes with mixed resins, filled into cylinders of different volume, appropriate size and throughput, you can optionally insert a device for measuring conductivity. In Germany, this practice is adopted: when the resin mass has depleted itself, the bottles are dehydrated (for weight reduction) and sent to the nearest exchange office, where they receive regenerated in exchange ( Hrist-Minisnil; manufacturer: With hrist Gmb N, 7250 Leonberg , P f . 1251, you can get help about the service). What is achieved by the desalination apparatus? It goes without saying that its performance depends on the stiffness of the incoming tap water. In addition, each device, depending on the volume, has a different hourly output. For example, take the standard models P-6, P-12 and P-21, filled with an equal amount of artificial resin (kg ):

The water passed through the desalination apparatus can be equated to distilled water. Distilled water is biologically dead; Water in this form can not be used for breeding fish. But to get excellent spawning water, it should only be diluted a little. With the help of the so-called cross rule, the desired mixture is very easy to make. Of course, a characteristic of tap water is required first. Example: we need spawning water with an index of 4 ° dN, and the rigidity of our tap water is 20 ° dN. Result: 16 parts of distilled water and 4 parts of tap water give a mixture with 4 ° dN. In the presence of a conductivity meter, the spawning water mixture can also be calculated from the NS index.

Example: our completely desalted water has a residual conductivity of 2 nS , and tap water has 520 nS. Requires spawning water with an index of 60 nS. Result: if you mix 460 parts of distilled water with 58 parts of tap water, we will get spawning water with an indicator of 60 nS.

Use of activated carbon and peat

And coal and peat are different - this is a common truth. So, if both of these materials you intend to use for reproduction of fish, you first need to try them. About their impact you need to know everything for sure! Absorption capacity of activated carbon is especially important because coal must detain all poisons (or substances that can become such). Bone coal has a particularly high absorption capacity: it is degreased by dry distillation, ground and used as activated. Trade offers it for laboratory needs, and this also applies to water filtration. For filters in spawning tanks, what has already been said about ordinary filters is particularly important: in order that coal does not become contaminated excessively and does not become useless, here, first of all, another, filtering mass, mechanically absorbing water, is needed, for example, fine fiber perlon wool. A constant pH does not occur either in nature or in an aquarium. Good peat causes this figure to go down, that is, it acidifies water. To obtain accurate pH data before and after peat application, pH measurements should be performed three times a day (morning, afternoon and evening) at the same time. But how do you determine the extent of the peat's influence before (!) Its bookmarking? More often peat, offered by specialized trade, acidifies water very poorly. Therefore, when breeding fish, do not rely on data provided by the manufacturer on the package, but you should check them yourself. The easiest way to do this is by laying a handful of peat in 1 liter of distilled water, whose pH should be neutral - 7.0. Peat should be left for 24 hours so that it soaks up with water. If the pH value after this is above the 5.5 boundary, then this peat is unlikely to suit you. And why do you need peat when preparing spawning water? The fact is that peat in the maintenance and reproduction of tropical ornamental fish has long been attributed almost magical properties. Modern research confirms the positive effect of peat on water due to its antifungal and bactericidal properties. However, the same effect can be achieved using chemicals (rivanol, methylene blue, etc.). And some even say that peat contains a female hormone that positively influences the desire of fish to spawn. If this is true, then success in breeding is affected not by a low pH, but by the presence or absence of a material such as peat.

Ultraviolet lamps and the world of bacteria

No matter how high the role of bacteria in connection with individual processes (for example, for the decomposition of toxic substances), the aquarist in the reproduction of fish is not very happy with their presence: he uses antifungal and bactericidal materials (eg peat) to protect his pet's eggs . Ultraviolet rays have a disinfecting effect on germs, embryos of plants and animals, provided that they are not surrounded by a protective coating. Sterilized spawning water has advantages in any case. Use an ultraviolet lamp - for example, known for many years, " hv " ( Wiegand) - is supposed to follow the filtering. The light of such a lamp should not penetrate directly into the aquarium water, because it harms the development of the eggs. The lamp has the form of a luminescent tube, covered with an additional glass shell with an inlet and an outlet for water. The filtered aquarium water is run through an isolated ultraviolet tube and is washed by the flow.

The use of ultraviolet lamps is also recommended for quarantine aquariums. However, the use of such radiators is possible only for water with a low content of nitrates. With prolonged use, ultraviolet rays tend to act in both directions - both oxidizing and restoring. And the restoration of nitrites from nitrates is a process not desirable for the aquarium.

Ozonation of water

In our time, ozone is increasingly used for disinfection of drinking water. Ozone is a compound of three oxygen atoms (O3), that is, an active form of oxygen and the strongest of the oxidizing agents used in practice with bactericidal properties. In a large concentration, ozone has a burning effect on the mucous membrane (especially respiratory organs) - sufficient caution in order not to use this remedy for a long time and directly in the aquarium.

But what are the qualities of ozone that are important for use in aquarium farming: the destruction of bacteria, the destruction of organic substances and (which, however, less interesting for fans to breed fish) - the creation of a high oxidation-reduction potential. All these qualities together justify the use of ozone. Just like ultraviolet light, ozone enters the aquarium water through the contact tube, after which a gas is formed in the ozonizer (high-voltage transformer with a discharge chamber) and, mixed with the air from the membrane pump, is injected into the depth of the contact tube through the outlet. The effect of ozone on water occurs during this short contact. Evaporation of ozone, which subsequently evaporates, is not stable: at room temperature it decomposes again, turning into less active oxygen. Ozone, like ultraviolet rays, destroys bacteria. The question is only whether there are any useful bacteria among them. In principle , neither ozone nor UV rays make any distinctions, but these bacteria are not contained in free water: they live in the soil at the bottom and in the substrate of biological filters. The rapid decrease in the number of microorganisms in the water makes itself felt by the fact that caviar develops better. In addition, ozone is used in border areas of aquaria, for example, when taking quarantine measures or when treating diseases. The most effective ozonizers of the firm " Sander " , because the air supplied to them by the air pump is really dry. In general, it is recommended to purchase an air dryer of the same firm as the ozonizer. Ozonizers are of different sizes, calculated for 10-1000 mg of ozone. It is recommended to choose the smallest device for breeding fish.

Hyukstedt, often cited by the coryphaeus of modern aquarium chemistry, speaking of ozonation, warns: "It is bad to overdo it here; Ozone as an aid can not be used for a long time. Let's not force the device to work continuously because we have it. Ozone makes water very clean, and since an amateur always wants it to become even cleaner, it also includes an ozonator for a long time. "