What aquarium filter do you use?
Look at the aquarium statistics on the forum - !

Aquael Aquarium Filter
Aquarium filter Atman
Eheim aquarium filter
Aquarium filter Fluval
Hydor Aquarium Filter
JBL aquarium filter
Jebo aquarium filter
Aquarium filter Dophin
Resun aquarium filter
Sera aquarium filter
Aquarium filter Sicce
SunSun Aquarium Filter
Tetra aquarium filter
Minjiang aquarium filter
Aquarium filter ADA
Aquarium filter Juvel Juwel
Aquarium filter Triton Triton
Dennerle aquarium filter
Barbus aquarium filter

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Super article! At one time, when my external filter flew off, I didn’t have such a competent article at hand. Bottom line: now in a 300l aquarium I have two filters hanging on both sides: a mechanical and a combined biofilter. Extremely satisfied with both. For my taste, an external filter is better. I was lucky with the purchase, but they can advise in the store such that even crying. It costs a lot of money, but in practice an ordinary mechanical filter. You need to know what it looks like what you need, and go to the store armed. It’s better, of course, not in a hurry, but to consider in advance the options for buying a filter for your aquarium, and this article is undoubtedly a good helper for a novice aquarist in this. Thanks!

Hello Yana!
As far as I remember, you, on the contrary, cursed at external aquarium filters on the FanFishka forum. They said they were hard to clean and spin!? Here you say that you prefer them, but at the same time you now have two internal filters in the aquarium?! What to believe?
I understand, the question is rhetorical - but still! What filter are you calling for?

Sincerely,

Well, I write what I like, the filters that I have now are much better than the external filter) "I have two filters hanging on both sides: a mechanical and a combined biofilter. I'm terribly satisfied with both. For my taste, it's better than an external filter."
I can sometimes write clumsily, but I'm always happy to explain my scribbles)))
I didn't like using an external filter!!! Bulky, inconvenient to clean, pipes are everywhere, and the rail through which water flows into the aquarium is constantly clogged, and it’s just the most difficult thing to wash it.
With a mechanical filter, everything is clear as two times two five. He took out a sponge, easily removed everything removable, washed it and put it back. With a biofilter, almost everything is the same (I have exactly the same copy as presented as an example in this article), only one more compartment to wash, but it can also be easily removed and washed. They clean wonderfully, despite the fact that I have goldfish, rather dirty creatures. In general, I am FOR a mechanical and biofilter combined!
Z.Y. I categorically apologize for the fact that I did not clearly describe my preferences. I hope the second time I redeemed myself)

Mouse, Hello!
Thank you for the kind words and compliments!

The topic of HC sterilizers is quite extensive and one can talk about it for a long time.
Alas, while there is no full-fledged article on this topic on the FF. But, I can say unequivocally that UV sterilizers are a good thing, but additional. There are many opinions, many FOR and AGAINST on this issue, but still regular water treatment with a sterilizer gives its advantages. The main disadvantages are the price, good sterilizers with good throughput are expensive. Sterilizers that are sold with filters are usually rather weak.
Is it possible to do without a sterilizer - YES! And three times, YES! Why? Everything is very simple - if you monitor the aquarium, take care of it, if it has a stable biobalance, etc. - you don't need a sterilizer. And vice versa, if a person does not understand what an aquarium is and perceives it as a TV set, then no UV sterilizer will help from aquatic troubles!
Judging by what you said about your aquarium, everything is OK with you - a normal number of fish, live plants ... You understand what balance and other aquas are. wisdom.

I confess to you honestly, periodically (2 times a year))) I think about HC, but for 15 years of aquatic practice I have not bought it. And now, when I’ve been busy with herbalism and aquascape... and the aquarium has turned into a lush, healthy, beautiful oasis... I understand that the best device for aqua is the aquarist himself))) Gadgets make life easier, but without proper attention and care, they are useless.

Sincerely,

Z.Y. Come to us, I suggest there to communicate. At the same time, we will ask the people what they think about this.

I think it depends on the filter setting. Recently I took myself a small Chinese filter of an incomprehensible brand, I need it for aerated. So, it has two exits - two nozzles. If one plug blows strongly. If you open both blowing weakly.

Hello! Please tell me about the choice of filter. I have a 100l aquarium. some grass, anubias and moss. neonki 6pcs, catfish 4pcs, barbs 4pcs, shrimp 5pcs. Light metalologen 70v, internal filter, CO2. I am a beginner and there is a test of the pen, so to speak. But I plan to buy a 180l jar and make an herbalist with a small amount of fish and shrimp. And now I have the choice of an external filter, this is jbl e901. EHEIM4+350 or 250 can you recommend another EHEIM. In the characteristics to them they write that the flow of water can be regulated, but I don’t understand how. Should I install a faucet?

Sergey, all external filters have taps with which you can regulate the flow. But it is not recommended to squeeze them especially. I used the external JBL - a good, silent filter. I can't speak for Eichmann. I recommend that you talk to the guys on our forum on this topic.

Haven't looked at Hydor filters? I recently ordered a Prime 30 in Akvionics, I'm looking forward to it, I want to use it for 7000 rubles, it's interesting to compare the price and quality myself.

Hello, there is an option to hang a 200l filter boyu sp1800b (750) liters per hour in an aquarium for mechanical, and pour zeolite into a small aqua el (300 liters per hour) for chemical treatment, how effective do you think it is. Population 8 zebrafish, 8 neon, 2 ancitrus, 200 grams of shrimp, I'm planning acanthophthalmus.

How to choose an external aquarium filter?

The external filter, compared to the internal filter, has many advantages - a larger volume of filter materials, it does not take up space in the aquarium, it needs to be cleaned less often.

When choosing an external filter, there is something to think about - it is easy to get confused in such a variety of brands and models.

Here short review series of the most popular filters to help you make your choice.

Tetra EX-400, 600, 800, 1200 plus

It is the most popular filter series, accounting for over 30% of sales in terms of the number of filters sold.

The phenomenon of such popularity is explained simply - a well-known name, affordable price.

1. Convenient design:

Each filler is in a separate tray

For cleaning, the filter can be easily detached using a special adapter.

There is a button for the initial launch of the filter

2. Warranty obligations:

Warranty period - 3 years

In Moscow, St. Petersburg and EKB there is a service center for warranty and post-warranty repairs

All are on sale Consumables and spare parts

3. Low noise operation - EX 400, 600, 800 plus filters are absolutely silent, the EX 1200 plus filter emits a moderate noise characteristic of high-performance filters.

4. Convenient handle for carrying the filter to the place of cleaning and back.

Eheim Classic 2211, 2213, 2215, 2217

External filters of the Eheim Classic series have been produced without special innovations for several decades. Despite the fact that Eheim has developed and successfully markets several series of more modern and "advanced" external filters, the Eheim Classic series is still very popular with aquarists.

The reason for this popularity is the simplicity of the design, which determines the high reliability, as well as the price. The transfer of the production of these filters to China largely contributed to the price reduction. That is, it is impossible in principle to purchase Eheim Classic series filters made in Germany, because they are no longer produced at a factory in Germany.

1. The filter is designed so that water enters at the bottom of the canister and exits at the top, which guarantees the passage of water through all stages of filtration, a “short circuit” of the water flow, which is possible with a loose fit of the baskets in more modern filters, is impossible here in principle .

2. The absence of "extra" connections in the form of adapters, buttons for quick launch, etc. provides increased protection against leaks.

3. High-quality fillers from Eheim are included in advanced configurations. But if you do not want to overpay for them, there is an opportunity to take cheaper options, without filter media, and fill them to your liking.

4. No baskets for fillers reduces the filter's resistance to water flow.

5. Double detachable taps that act as an adapter make it easy to detach the filter for cleaning. (Attention! The Classic 2211 model is sold without taps, taps are purchased separately.)

6. Warranty - 3 years from the date of sale, there is a branded service center in Moscow. Spare parts can also be found if needed.

1. The reverse side of the simplicity of the design is a number of disadvantages due to it:

The absence of a start button will force you to start the filter from time to time in the "old-fashioned" way, by taking a deep breath, holding the filter outlet hose in your mouth, which is not very convenient.

The absence of baskets for fillers will make more manipulations when cleaning the filter, or it will require the use of special bags (this will be a prerequisite for using activated carbon or peat).

2. The noise level, although it can be called quite low, is still higher than that of more modern counterparts.

3. There is no carrying handle, which makes filter maintenance (especially older models) not as convenient as competitors.

*Note: The Eheim Classic 2211 filter - for some reason the manufacturer sells it practically in a “naked” form - in addition to the filter itself, the package includes only hoses, a flute and an inlet pipe, as well as two sponges for fine and coarse cleaning. Cranes that allow more or less convenient maintenance of this filter are sold separately, while their price is prohibitive - almost half the cost of the filter. As a result, the 2211 filter with taps and fillers will cost almost more than 2213 with all the necessary components. For this reason, we sell this filter only when the buyer himself knows what he needs and is ready to solve these problems on his own.

AquaEl Unimax 150, 250, 500, 700

The Polish company AquaEl has long been transformed from a 2nd tier manufacturer from Eastern Europe into one of the trendsetters in the aquarium equipment market. Almost every problem that arises before the manufacturer of aquarium equipment, they try to solve in an original way. AquaEl Unimax external filters also offer some interesting technical solutions.

1. Exceptionally quiet operation - even on the powerful 500 and 700 models.

2. They have all the "standard" options of modern external filters - a pump for initial start-up, a carrying handle, separate containers for fillers.

3. Models 500 and 700 are equipped with special wheels so that they can be easily and conveniently moved to the place of cleaning, because the filters filled with water are quite heavy.

4. A UV sterilizer can be built into any AquaEl Unimax filter; a regular installation site is provided for it. Thus, it is possible to provide UV sterilization without installing an additional device and extra hoses in the nightstand, which is very convenient.

5. Models 500 and 700 have 2 pumps, and, respectively, 2 inlet and outlet hoses, which provides increased reliability (even if one of the pumps fails, the second one will continue to work) and better distribution of water flows in the aquarium.

6. Warranty for AquaEl Unimax filters - 3 years from the date of sale, there is a service center in Moscow.

7. In addition to Eheim - AquaEl is the only manufacturer that produces its external filters in Europe (Poland).

1. When selling filters of older models (500, 700), we have repeatedly encountered the fact that they simply do not fit into the cabinet. Before ordering such a filter, you should make sure that there is enough space in the cabinet for it - or be ready to install the filter next to the aquarium.

2. Biofilter media is not much better than Tetra filter media.

Sera fil Bioactive + UV

The series of external filters Sera fil Bioactive is especially remarkable in that it includes filters with a UV sterilizer already built in, while the difference in price between models with UV sterilizers is so small that it seems to us that if you chose this product firms - it is better to take a model with a sterilizer than without it.

1. Standard set - carrying handle, quick start button, filter quick release adapter, fillers are in separate trays.

2. The built-in UV sterilizer will protect the fish from pathogenic microbes, remove the yellowish tint of the water and make it easier to deal with its turbidity.

3. Supplied with sera siporax, a high-performance filler, and sera filter biostart, a special preparation for quick biological start of the filter.

4. In operation, these filters are quite quiet.

5. Warranty - 2 years, performance warranty obligations carried out by the seller.

1. Models 250 and 400 have a rather bulky design (rather wide in diameter), which means you need to make sure that they will fit into the cabinet.

2. The “idle” water tube (through which water enters the lower part of the filter) has a wide cross section - on the one hand, this reduces the resistance to water flow, but on the other, it steals the useful volume of the filter.

3. For UV sterilizers, only "native" sera lamps can be used, which, however, are not difficult to find on sale (in particular, the lamp for the 130+UV model, and 250/400+UV).

Eheim Professional 3

"Top" line of external filters from a German manufacturer.

The Eheim Professionel 3 series includes all the engineering research and development, as well as the aspirations of many aquarists.

1. Exceptional quiet operation.

2. Low power consumption.

3. Filter start button, detachable adapter, special recesses for easy carrying.

4. The filter is fully "charged" with high-performance Eheim fillers, including Eheim Substrate Pro, which guarantees high quality water purification (except for model 2080).

5. Warranty - 3 years, a service center operates in Moscow.

1. Relatively high price

The most important thing is that whatever filter you buy, do not make a mistake, the main thing is to choose it according to the volume of your aquarium.

Starting and maintaining an external aquarium filter How to properly start and maintain an external aquarium filter?

It is rather difficult to overestimate the role of filtration in an aquarium - the purity of water depends on the quality of filtration - and not only optical, but also chemical, often invisible to the eye. And as a result, the health and life of the inhabitants of the aquarium depends on how correctly the filter is launched and maintained.

Starting an external aquarium filter

So, the brand new filter is ready to be installed. We will not describe the process of installing pipes, hoses, various adapters, etc., since this process looks different for each filter, we will focus only on general points:

First of all, remove the filter media and sponges that the filter is equipped with from the bags. It sounds funny, but sometimes people forget to do it.

Rinse the case, baskets (if any) and all fillers and sponges with warm water to wash off industrial dust. If this is not done, nothing terrible will happen, but you don’t need extra dirt in the aquarium, do you? It is advisable to wash off, wipe off the lubricants and oil in the rotor and wherever you get it.

Lay all fillers as indicated in the instructions for the filter.

Biological activation of the filter.

If you start the aquarium at the same time as the filter, it is especially important to biologically activate the external filter. But even if you install a filter instead of the old one, or instead of an internal filter, it will not be superfluous and will allow the filter to quickly settle with beneficial bacteria and reach “full power”.

It is very simple to do this - just apply one of the special preparations to the bottom layer of the sponges (or rather, the first one along the water flow) or to the porous ceramic filler, if the filter is equipped with such.

The most popular drugs for these purposes are presented in our store:

Tetra Bactozym and Tetra SafeStart

sera filter biostart

Dennerle BactoClean

We do not undertake to judge which one is better - all 4 drugs are made in Germany, and the Germans usually have everything in order with quality, so take any of them at your discretion.

Important: In order for bacteria to successfully settle in the filter, it is necessary to prepare the water in advance. If the aquarium is already running, this will not require additional efforts, and if the aquarium is fresh and tap water is poured, it must be prepared with special air conditioners that eliminate chlorine and heavy metals - these substances are just as (if not more) harmful to beneficial bacteria as and for fish.

After activation, you can finally assemble, connect and put the filter into operation, following the instructions for use.

At first (especially if the aquarium is new), the water may become cloudy and remain so for quite a long time (usually about 1-2 weeks, sometimes up to a month). This is due to the fact that a large number of microorganisms begin to multiply in the water, serving as a nutrient medium for each other - bacteria and ciliates. Usually such turbidity is called "bacterial" and it does not pose any danger to the population of the aquarium. It passes with time, on its own - the main thing in the first months of the life of the aquarium is to feed the fish very sparingly, avoiding overfeeding (all food should be eaten in 2-3 minutes).

Often beginner aquarists take turbidity as a sign of some serious problem and begin to endlessly change the water, which only delays the process of establishing biological balance.

So, the filter is running, water circulates through the fillers, and the owner, pleased with himself, is watching life in the aquarium.

A couple of tips:

Try not to leave excess length of hoses - cut off the excess so that the filter can be easily serviced later. Every extra centimeter of hose is an additional resistance to water flow, which reduces the performance of the filter. But do not overdo it - measure 7 times, cut 1 time.

It will not damage the inlet pipe of an external filter (which is located in the aquarium) instead of a regular grid, which traps large dirt (leaves, etc.) and does not allow fish to get inside the filter, install a special prefilter - it will serve as the 1st filtration stage from coarse dirt, which will allow less frequent maintenance of the external filter itself, washing the prefilter sponges from time to time. Currently, such prefilters are manufactured by Eheim.

Filter maintenance.

A clear indication for filter cleaning is a noticeably reduced water flow - this can be determined either visually if the "flute" is located above the water level, or by placing your hand under the water flow - and compare the sensations with those when the filter was just started. If the difference is noticeable - it's time to clean the filter ..

However, we would not recommend waiting for such a decrease in performance each time and cleaning the filter a little more often, especially if the aquarium has or occasionally has problems with the growth of unwanted algae (scale on glass, soil and plants, “beard”, etc.). ).

The fact is that the filter only retains dirt on its sponges, which at the same time physically remains in the aquarium water and continues to slowly dissolve and be processed by all kinds of bacteria. If the aquarium is densely populated with plants that have time to “process” all these substances, using them for their own growth, there is no big problem. But if there are few or no plants in the aquarium, all these substances will go to “feed” algae (do not confuse with plants), which will joyfully and rapidly begin to grow everywhere.

Here are a few basic rules for cleaning the external filter:

Sponges for coarse filtration and non-porous ceramics (manufacturers often put them in the 1st basket) can be safely washed under the tap, directly with tap water.

Biological filler (porous ceramics, all kinds of balls, rings, etc.) should be washed only from coarse mechanical dirt, simply by lowering it into a container with water that has just been taken from the aquarium. This will preserve the colonies of beneficial bacteria grown with such difficulty. If you rinse these fillers simply "under the tap" - most of these bacteria will die.

Manufacturers recommend changing a fine cleaning sponge (white synthetic winterizer) with each cleaning - but experience shows that they are quite capable of surviving at least 1 flush (you can under the tap). If the original fine cleaning sponges cannot be purchased, they can be replaced with universal fine filtration cotton - it is easily cut (and even torn by hand) and can be placed in any filter.

Do not forget to clean the engine compartment and the filter rotor - a lot of dirt accumulates there too and even colonies of algae and bacteria grow. If this is not done, after a while the filter may simply stop. For these purposes, you can use special brushes.

From time to time it is useful to clean the hoses - for this purpose it is very convenient to use flexible brushes, for example JBL Cleany - versatile and inexpensive.

If your filter is equipped with taps for separately shutting off the inlet and outlet water flows, we recommend that after the filter has been connected back to the hoses, first open the inlet channel, and after a few - the outlet channel - this will ensure that the filter is correctly filled with water and avoid the formation of air bubbles in the head of the filter and restart problems.

Biological water treatment
Biological purification of water includes the most important processes occurring in closed aquarium systems. By biological purification we will understand the mineralization, nitrification and dissimilation of compounds containing nitrogen by bacteria living in the water column, gravel and filter detritus. Organisms that perform these functions are always present in the thickness of the filter. In the process of mineralization and nitrification, nitrogen-containing substances pass from one form to another, but nitrogen remains in the water. Removal of nitrogen from the solution occurs only during denitrification (see section 1.3).
Biological filtration is one of four ways to purify water in aquariums. Three other methods - mechanical filtration, physical adsorption and water disinfection - are discussed below.
The scheme of water purification is shown in fig. 1.1., and the nitrogen cycle in the aquarium, including the processes of mineralization, nitrification and denitrification, is shown in fig. 1.2.
Place of biological treatment in water purification process
Rice. 1.1. Place of biological treatment in the process of water treatment. From left to right - biological stonecrop, mechanical filtration, physical precipitation, disinfection.
Nitrogen cycle in aquarium closed systems
Rice. 1.2. Nitrogen cycle in aquarium closed systems.

1.1 Mineralization.
Heterotrophic and autotrophic bacteria are the main groups of microorganisms that live in aquariums.
The note is not from the author's book.
Heterotrophs (other Greek - "different", "different" and "food") - organisms that are not able to synthesize organic substances from inorganic ones by photosynthesis or chemosynthesis. For the synthesis of organic substances necessary for their life activity, they require exogenous organic substances, that is, produced by other organisms. During digestion, digestive enzymes break down the polymers of organic matter into monomers. In communities, heterotrophs are consumers of various orders and decomposers. Almost all animals and some plants are heterotrophs. According to the method of obtaining food, they are divided into two opposing groups: holozoic (animals) and holophytic or osmotrophic (bacteria, many protists, fungi, plants).
Autotrophs (ancient Greek - self + food) - organisms that synthesize organic substances from inorganic ones. Autotrophs make up the first tier in the food pyramid (the first links of food chains). They are the primary producers of organic matter in the biosphere, providing food for heterotrophs. It should be noted that sometimes it is not possible to draw a sharp boundary between autotrophs and heterotrophs. For example, the unicellular alga Euglena green in the light is an autotroph, and in the dark it is a heterotroph.
Sometimes the concepts of "autotrophs" and "producers", as well as "heterotrophs" and "consumers" are mistakenly identified, but they do not always coincide. For example, blue-greens (Cyanea) are capable of producing organic matter themselves using photosynthesis, and consuming it in finished form, and decomposing it to inorganic substances. Therefore, they are producers and decomposers at the same time.
Autotrophic organisms use the inorganic substances of soil, water and air to build their bodies. The source of carbon is almost always carbon dioxide. At the same time, some of them (phototrophs) receive the necessary energy from the Sun, others (chemotrophs) - from chemical reactions of inorganic compounds.

Heterotrophic species utilize the organic nitrogenous components of aquatic animal excretions as an energy source and convert them into simple compounds such as ammonium (the term "ammonium" refers to the sum of ammonium (NH4+) and free ammonia (NH3) ions, analytically defined as NH4-N ). The mineralization of these organic substances is the first stage of biological treatment.
Mineralization of nitrogen-containing organic compounds can begin with the breakdown of proteins and nucleic acids and the formation of amino acids and organic nitrogenous bases. Deamination is a mineralization process during which the amino group is cleaved off to form ammonium. The subject of deamination can be the splitting of urea with the formation of free ammonia (NH3).

Such a reaction can proceed purely chemically, but the deamination of amino acids and their accompanying compounds requires the participation of bacteria.

1.2. Water nitrification.
After the organic compounds are converted by heterotrophic bacteria into an inorganic form, biological purification enters the next stage, called "nitrification". This process is understood as the biological oxidation of ammonium to nitrites (NO2-, defined as NO2-N) and nitrates (NO3, defined as NO3-N). Nitrification is carried out mainly by autotrophic bacteria. Autotrophic organisms, unlike heterotrophic ones, are able to assimilate inorganic carbon (mainly CO2) to build the cells of their body.
Autotrophic nitrifying bacteria in freshwater, brackish and marine aquaria are mainly represented by the genera Nitrosomonas and Nitrobacter. Nitrosomonas oxidizes ammonium to nitrite, while Nitrobacter oxidizes nitrite to nitrate.
Keeping fish in closed systems S. Spott
Both reactions go with the absorption of energy. The meaning of equations (2) and (3) is to convert toxic ammonium into nitrates, which are much less toxic. The efficiency of the nitrification process depends on the following factors: presence of toxicants in the water, temperature, dissolved oxygen content in the water, salinity and filter surface area.

Toxic substances. Under certain conditions, many chemicals inhibit nitrification. When added to water, these substances either inhibit the growth and reproduction of bacteria, or disrupt the intracellular metabolism of bacteria, depriving them of their ability to oxidize.
Collins et al. (Collins et al., 1975, 1976) and Levine and Meade (1976) reported that many antibiotics and other drugs used to treat fish did not affect nitrification processes in freshwater aquaria, in while others have been found to be toxic to varying degrees. Parallel studies in sea water have not been carried out, and the results presented should not be extended to marine systems.
Given in three these works the data are presented in table. 1.1. The results of the studies are not quite comparable due to differences in the methods used.

Table 1.1. Effect of therapeutic rates of diluted antibiotics and medicaments on nitrification in freshwater aquaria (Collins et al., 1975, 1976, Levine and Meade, 1976).
Influence of therapeutic rates of dissolved antibiotics and medicinal preparations on nitrification in freshwater aquariums
Collins et al. studied the effects of drugs in water samples taken directly from operating fish tanks with biofilters. Levine and Mead used pure bacterial cultures for the experiments. The methods used by them, apparently, were more sensitive than the usual ones. Thus, in their experiments, formalin, malachite green, and nifurpyrinol were moderately toxic to nitrifying bacteria, while Collins et al showed the same drugs to be harmless. Levine and Mead believed that the discrepancies were due to the higher content of autotrophic bacteria in pure cultures and the inactivation threshold would be higher in the presence of heterotrophic bacteria and at a higher concentration of dissolved organic substances.
From the data in Table. 1.1. it can be seen that erythromycin, chlorotetracycline, methylene blue and sulfanilamide have a pronounced toxicity in fresh water. The most toxic among the substances studied was methylene blue. The results obtained when testing chloramphenicol and potassium permanganate are contradictory.
Both Collins et al. and Levine and Mead agree that copper sulfate does not significantly inhibit nitrification. Perhaps this is the result of the binding of free copper ions with dissolved organic compounds. Tomlinson and others (Tomlinson et al., 1966) found that heavy metal ions (Cr, Cu, Hg) had a much stronger effect on Nitrosomonas in pure culture than in activated sludge. They suggested that this was due to the formation of chemical complexes between metal ions and organic substances. Long-term exposure to heavy metals is more effective than short-term exposure, apparently due to the fact that the adsorption bonds of organic molecules were completely used.

Temperature. Many bacterial species can tolerate large fluctuations in temperature, although their activity is temporarily reduced. An adaptation period called temporary temperature inactivation (TTI) often occurs with sudden changes in temperature. Usually, VTI is noticeable during a sharp cooling of water; an increase in temperature, as a rule, accelerates biochemical processes and therefore the adaptation period may go unnoticed. Srna and Baggaley (1975) studied the kinetics of nitrification processes in marine aquaria. An increase in temperature of only 4 degrees Celsius led to an acceleration in the oxidation of ammonium and nitrite by 50 and 12%, respectively, compared with the initial level. With a decrease in temperature by 1 degree Celsius, the rate of ammonium oxidation decreased by 30%, and with a decrease in temperature by 1.5 degrees Celsius, the rate of oxidation of nitrites decreased by 8% compared with the initial conditions.

water pH. Kawai et al. (1965) found that at pH less than 9 nitrification in sea water is suppressed more than in fresh water. They attributed this to the lowered natural pH in fresh water. According to Saeki (1958), ammonium oxidation in freshwater aquariums is suppressed by lowering the pH. The optimum pH value for ammonium oxidation is 7.8 for nitrite oxidation 7.1. Seki considered the optimal pH range for the nitrification process to be 7.1-7.8. Srna and Baggali showed that marine nitrifying bacteria were most active at pH 7.45 (range 7-8.2).

oxygen dissolved in water. A biological filter can be compared to a huge breathing organism. When working properly, it consumes a significant amount of oxygen. The oxygen requirements of aquatic organisms are measured in units of BOD (biological oxygen demand). The BOD of a biological filter depends partly on nitrifiers, but it is mainly due to the activity of heterotrophic bacteria. Harayama (Hirayama, 1965) showed that a large population of nitrifiers was active at high biological oxygen demand. It passed sea water through a layer of sand of an active biological filter. Before filtering, the oxygen content in the water was 6.48 mg/l, after passing through a layer of sand 48 cm thick. it dropped to 5.26 mg/l. At the same time, the content of ammonium decreased from 238 to 140 mg.eq./l., and nitrite - from 183 to 112 mg.eq./l.
Both aerobic (needs O2 for life) and anaerobic bacteria (does not use O2) are present in the filter bed, but aerobic forms predominate in well-aerated aquariums. In the presence of oxygen, the growth and activity of anaerobic bacteria is inhibited, so the normal circulation of water through the filter inhibits their development. If the oxygen content in the aquarium decreases, either an increase in the number of anaerobic bacteria occurs, or a transition from aerobic respiration to anaerobic respiration occurs. Many products of anaerobic metabolism are toxic. Mineralization can also occur at a reduced oxygen content, but the mechanism and end products in this case are different. Under anaerobic conditions, this process proceeds more as an enzymatic than as an oxidative one, with the formation of organic acids, carbon dioxide and ammonium instead of nitrogenous bases. These substances, along with hydrogen sulfide, methane and some other compounds, give the suffocating filter a putrid odor.

Salinity. Many species of bacteria are able to live in waters that fluctuate significantly in ionic composition, provided that changes in salinity occur gradually. ZoBell and Michener (1938) found that most of the bacteria isolated from seawater in their laboratory could be grown in freshwater. Many bacteria have even survived a direct transplant. All 12 species of bacteria, considered exclusively "marine", were successfully transferred to freshwater by gradually diluting with sea water (5% fresh water was added each time).
Biological filter bacteria are very resistant to salinity fluctuations, although if these changes are large and sudden, bacterial activity is suppressed. Srna and Baggaley (1975) showed that an 8% decrease in salinity and a 5% increase in salinity had no effect on the rate of nitrification in marine aquaria. At normal water salinity in marine aquarium systems, the nitrifying activity of bacteria was maximum (Kawai et al., 1965). The intensity of nitrification decreased both with dilution and with an increase in the concentration of the solution, although some activity was retained even after the water salinity was doubled. In freshwater aquaria, bacterial activity was at its highest before the addition of sodium chloride. Immediately after the salinity equaled the salinity of sea water, nitrification ceased.
There is evidence that salinity affects the rate of nitrification and even the amount of end products. Kuhl Mann (Kuhl and Mann, 1962) showed that nitrification proceeded faster in freshwater aquarium systems than in marine systems, although nitrite and nitrate were higher in the latter. Kawai and others (Kawai et al., 1964) obtained similar results, which are presented in fig. 1.3.
The number of bacteria in the filtration layer in small freshwater and marine aquarium systems after 134 days
Rice. 1.3. Filter bed bacteria counts in small freshwater and marine aquarium systems after 134 days (Kawai et al., 1964).

filter surface area. Kawai et al. found that the concentration of nitrifying bacteria in a filter is 100 times higher than in water flowing through it. This proves the importance of the size of the contact surface of the filter for nitrification processes, since it allows bacteria to attach. The largest surface area of ​​the filter bed in aquariums is provided by gravel (soil) particles, and the nitrification process occurs mainly in the upper part of the gravel filter, as shown in Fig. 1.4. Kawai et al. (1965) determined that 1 gram of sand from the top layer of the filter in marine aquariums contains 10 to the 5th degree of bacteria - ammonium oxidizers 10 to the 6th degree - nitrate oxidizers. At a depth of only 5 cm, the number of microorganisms of both types was reduced by 90%.
Concentration and activity of nitrifying bacteria at different filter depths in a marine aquarium
Rice. 1.4. Concentration (a) and activity (b) of nitrifying bacteria at different filter depths in a marine aquarium (Yoshida, 1967).

The shape and particle size of the gravel is also important: fine grains have more surface area for bacteria to attach to than the same amount by weight of coarse gravel, although very fine gravel is undesirable as it makes water difficult to filter. The relationship between dimensions and their surface area is easy to demonstrate with examples. Six cubes weighing 1 gr. They have a total of 36 surface units, while one cube weighing 6 g. It has only 6 surfaces, each of which is larger than the individual surface of the small cube. The total area of ​​six 1 gram cubes is 3.3 times the surface area of ​​one 6 gram cube. According to Seki (Saeki, 1958), optimal size particles of gravel (soil) for filters is 2-5 mm.
Angular particles have a larger surface area than round ones. A ball has the smallest surface area per unit volume compared to all other geometric shapes.
Accumulation of detritus (The term "detritus" (from Latin detritus - abraded) has several meanings: 1. Dead organic matter, temporarily excluded from the biological cycle of nutrients, which consists of the remains of invertebrates, secretions and bones of vertebrates, etc.; 2 - a collection of small undecomposed particles of plant and animal organisms or their secretions, suspended in water or settled on the bottom of a reservoir) in the filter provides additional surface and improves nitrification. According to Seki, 25% of nitrification in aquarium systems is due to detritus-inhabiting bacteria.

1.3. Dissimilation
The nitrification process results in a high degree of oxidation of inorganic nitrogen. Dissimilation, "nitrogen respiration", or reduction process, develops in the opposite direction, returning the end products of nitrification to a low oxidation state. In terms of total activity, the oxidation of inorganic nitrogen significantly exceeds its reduction, and nitrates accumulate. In addition to dissimilation, which ensures the release of part of the free nitrogen into the atmosphere, inorganic nitrogen can be removed from the solution by regularly replacing part of the water in the system, by uptake by higher plants, or by using ion exchange resins. The latter method of removing free nitrogen from solution is applicable only in freshwater (see section 3.3).
Dissimilation is a predominantly anaerobic process that takes place in filter layers that are deficient in oxygen. Bacteria are denitrifiers with a reducing ability, usually either complete (obligate) anaerobes or aerobes capable of switching to anaerobic respiration in an anoxic environment. As a rule, these are heterotrophic organisms, for example, some species of Pseudomonas, can reduce nitrate ions (NO3-) under conditions of oxygen deficiency (Painter, 1970).
In anaerobic respiration, dissimilatory bacteria take in nitric oxide (NO3-) instead of oxygen, reducing nitrogen to a compound with a low oxidizing number: nitrite, ammonium, nitrogen dioxide (N20), or free nitrogen. The composition of the final products is determined by the type of bacteria involved in the reduction process. If inorganic nitrogen is completely reduced, that is, to N2O or N2, the dissimilation process is called denitrification. In a completely reduced form, nitrogen can be removed from water and released into the atmosphere if its partial pressure in solution exceeds its partial pressure in the atmosphere. Thus, denitrification, in contrast to mineralization and nitrification, reduces the level of inorganic nitrogen in water.

1.4. "Balanced" aquarium.
A “balanced aquarium” is a system in which the activity of bacteria inhabiting the filter is balanced with the amount of organic energy substances entering the solution. According to the level of nitrification, one can judge the "balance" and suitability of the new aquarium system for keeping aquatic organisms - aquatic organisms. Initially, the high ammonium content is the limiting factor. Usually in warm water (above 15 degrees Celsius) aquarium systems, it decreases after two weeks, and in cold water (below 15 degrees) - for a longer period. The aquarium may be ready to receive animals within the first two weeks, but it is not yet fully balanced as many important groups of bacteria have not yet stabilized. Kawai et al. described the composition of the bacterial population of a marine aquarium system.
1. Aerobic. Their number for 2 weeks after planting the fish increased 10 times. The maximum number is 10 to the eighth degree of organisms in 1g. Filter sand - noted after two weeks. Three months later, the bacterial population stabilized at 10 to the seventh power of copies per gram. Filter sand.
2. Bacteria that decompose protein (ammonifiers). The initial density (10 to 3 ind./g) increased 100 times in 4 weeks. Three months later, the population stabilized at the level of 10 to 4 ind./gr. Such a sharp increase in the number of this class of bacteria was caused by the introduction of food (fresh fish) rich in protein.
3. Bacteria that decompose starch (carbohydrates). The initial population was 10% of the total number of bacteria in the system. Then it gradually increased, and after four weeks it began to decline. The population stabilized after three months at the level of 1% of the total number of bacteria.
4. Nitrifying bacteria. The maximum number of bacteria oxidizing nitrites was noted after 4 weeks, and the "nitrate" forms - after eight weeks. After 2 weeks, there were more "nitrite" forms than "nitrate" ones. The number stabilized at the level of 10 to the 5th degree and 10 to the 6th degree ind. respectively. There is a time difference between the decrease in ammonium content in water and oxidation at the beginning of nitrification, due to the fact that the growth of Nitrobacter is inhibited by the presence of ammonium ions. Efficient oxidation of nitrites is possible only after most of the ions are converted by Nitrosomonas. Similarly, the maximum nitrite in solution should occur before nitrate accumulation begins.
A high ammonium content in a new aquarium system may be caused by instability in the abundance of autotrophic and heterotrophic bacteria. At the beginning of the work of a new system, the growth of heterotrophic organisms exceeds the growth of autotrophic forms. A lot of ammonium formed in the process of mineralization is absorbed by some heterotrophs. In other words, it is impossible to clearly distinguish between heterotrophic and autotrophic ammonium processing. Active oxidation by nitrifying bacteria appears only after the reduction and stabilization of the abundance of heterotrophic bacteria (Quastel and Scholefield, 1951).
The number of bacteria in a new aquarium only matters as long as it does not stabilize for each type. Subsequently, fluctuations in the intake of energy substances are compensated by an increase in the activity of metabolic processes in individual cells without an increase in their total number.
Studies by Quastek and Sholefield (1951) and Srna and Baggalia showed that the population density of nitrifying bacteria inhabiting a filter of a certain area is relatively constant and does not depend on the concentration of incoming energy substances.
The overall oxidative capacity of bacteria in a balanced aquarium is closely related to the daily intake of oxidizable substrate. A sudden increase in the number of reared animals, their weight, the amount of feed introduced leads to a noticeable increase in the content of ammonium and nitrite in the water. This situation persists until the bacteria adapt to new conditions.
The duration of the period of increased ammonium and nitrite content depends on the magnitude of the additional load on the processing part of the water system. If it is within the maximum performance of the biological system, equilibrium under new conditions in warm water is usually restored after three days, and in cold water- much later. If the additional load exceeds the capacity of the system, the ammonium and nitrite content will constantly increase.
Mineralization, nitrification and denitrification are processes that occur more or less sequentially in a new aquarium. In an established - stable system, they go almost simultaneously. In a balanced system, the ammonium content (NH4-N) is less than 0.1 mg/l, and all nitrites that are captured are the result of denitrification. The processes mentioned above proceed in a coordinated manner, without lagging behind, since all incoming energy substances are quickly assimilated.

1.5 The device of the bottom filter - soil.
The device of gravel (ground) filters is preceded by the determination of general parameters, the preparation of the filter board and the calculation of the airlift. The device of airlifts is considered in section 5.1.
Primary requirements. Gravel filters fully provide the biological and mechanical water purification required for most even very large aquarium systems, therefore the requirements for biological and mechanical purification are the same and are as follows: the surface area of ​​the filter must be equal to the area of ​​the aquarium, the particle size of the gravel must be 2-5 mm ., the gravel should be sorted by particle size, the thickness of the filter layer should be the same over the entire filter area, the gravel particles should be of irregular angular shape, the water flow should be approximately 0.7*10-3 m/s, the minimum filter thickness should be 7.6 centimeters.
The distribution of bacteria in the filter layer directly depends on its thickness, which indirectly affects the efficiency of the processing of organic substances in water. Kawai et al showed that in a marine aquarium, heterotrophic bacteria were most numerous on the surface of the filter layer, and at a depth of 10 cm their number decreased to almost 90%. A similar trend persisted for autotrophic species. The population of ammonium and nitrite oxidizing bacteria, whose density in the surface layer was 10 to the 5th degree and 10 to the 6th degree ind./g., decreased by 90% at a depth of 5 cm. Based on this, Kawai et al. large surface. Yoshida (1967) reported that in marine aquariums, the maximum activity of nitrifying bacteria was noted in the upper layers of the filter (see Fig. 1.4). As the layer thickness increased, the activity sharply decreased. Thus, the requirement that the surface of the filter layer is equal to the area of ​​the aquarium is the main one.
Hirayama (Hirayama, 1965) showed that the dependence of the efficiency of processing organic substances on the thickness of the filter is indirect in cases where the OSF (filter oxidizing capacity) served as a criterion. BOS can be expressed as the rate of biological oxygen consumption - BOD / min. Conversely, the time required for water to pass through the filter should be positively correlated with RSF. Hirayama showed that thick filters have no advantage, since the time required for water to pass through the filter is proportional to its thickness. To prove this point of view, Hirayama set up an experiment in which waste water passed through four filters that differed only in thickness. The time required for water to pass through the filter was kept constant by measuring the water flow. At the end of the experiment, it turned out that the RSF remained the same, despite the fact that the thickness of the filters was different. Thus, thick filters require more water than thin ones.
filter boards. The filter board separates the filter layers from the bottom of the aquarium. Note: in modern aquaristics, such an arrangement of a bottom filter is called a false bottom. In aquarism, a false bottom is rarely used. It is important to tightly glue the edges of the board with the glass of the aquarium so that gravel (soil) does not wake up under it. For most aquariums, the filter board can be made from any porous material that will not corrode in water. The Niagara Falls and Mystic MarineLife aquariums use fiberglass reinforced corrugated sheets and a mesh of epoxy resin and fiberglass reinforced. In corrugated sheets with such circular saw equipped with a plastic thread cutter, slots should be cut perpendicular to the stiffeners. The width of the slot (Fig. 1.6.) is 1 mm, the length is 2.5 cm, the distance between the slots is five centimeters. After that, the panels are laid with the cuts down the aquarium and the joints are sealed with fiberglass tape (5 cm wide) and silicone glue. After the glue has completely hardened, you can pile on a layer of gravel (soil) and level it over the board.
When using a mesh, it is cut from above with a plastic sieve and fixed to the mesh with a fishing line or stainless steel wire. The joints are then sealed with silicone adhesive. Both sheets and nets should be separated from the bottom of the aquarium with special supports, such as concrete, or halves of PVC pipes of the required length, cut lengthwise and installed on the edge.
Keeping fish in closed systems S. Spott
Rice. 1.6. Cross section of an aquarium showing the arrangement of a corrugated fiberglass filter board.

It is important that water can circulate freely between the pads. Concrete stands are coated with three coats of epoxy, especially in marine aquariums, to prevent the concrete from eroding. The stands should not be attached to the filter board or to the bottom of the aquarium.
filter performance. An important aspect of biological treatment is filter performance, which is determined by the maximum number of animals that can live in a given aquarium system. Hirayama suggested the following formula for calculating the filter performance in marine aquariums (The equation is also valid for freshwater aquariums, but needs to be clarified).
Keeping fish in closed systems S. Spott
The left hand side of the equation describes the filter's Oxidation Capacity (OSP) expressed as the amount of O2 (in mg) consumed per minute.
Keeping fish in closed systems S. Spott
The right side of equation (4) characterizes the rate of "pollution" of water by animals. It is also expressed as the amount of O2 (in mg) consumed per minute.
As can be seen from formula (4), the oxidative capacity of the filter can be greater than or equal to the rate of "pollution" of water by animals. It is also important to note that the lower the mass of individual animals, the lower the performance of the aquarium system. In other words, the performance of a biological filter is not a simple function of the weight of the animals.
A system that can provide the vital activity of one fish weighing 100 g may not withstand the load of 10 fish weighing 10 g each. Suppose, in a hypothetical aquarium W=0.36m2, V=10.5 cm/min, D=36 cm. If the soil is uniform in size and R=4mm, then from equation (5) it follows that G=(1/4 )*100=25. Substituting these data into the left side of equation (4), we obtain the filter's oxidative capacity (OSF), which is equivalent to the rate of biological oxygen consumption - BOD / min.
Keeping fish in closed systems S. Spott
Suppose further that the aquarium contains fish weighing 200g. And their daily diet is 5% of body weight. From the right side of equation (4) (OSF denoted by X) it follows that:
Keeping fish in closed systems S. Spott
Table 1.2 shows the X values ​​for one fish, depending on its weight (in grams) and the amount of the daily ration (in % of body weight). From Table. 1.2. it follows that one fish weighing 200 g, whose daily ration is 5% of its body weight, creates a “load” on the filter equal to 0.69 OSF / min. At the same time, q=X/0.69=3.2/0.69=4.6 fish, that is, four fish can be kept in the aquarium.

Table 1.2. The load on the filter depending on the weight of one fish and the size of the daily ration (in % of body weight).
Keeping fish in closed systems S. Spott
This technique should be used with caution. The load on the filter changes as the animals grow, and its performance can be suddenly exceeded due to the death of fish or a sharp decrease in oxygen content.
As another example, let's determine whether it is possible to contain 10 fish of 50 g each in the aquarium from the first example. and one weighing 600g. at the same feeding rate - 5% of body weight daily. As can be seen from Table. 1.2., the load on the filter will be 10(0.21)+1(1.85)=3.95 OSF/min. The answer will be no, because the load on the filter exceeds its capacity, which is 3.2 OSF/min.

1.6. A practical guide to running a filter
Proper operation of a biological filter includes the steps to start up a new filter and ensure proper care of the existing filter.
Launching a new aquarium. During the start-up of a new filter, it is best to give it an increased load, that is, adapt it to a slightly increased load in terms of the number of animals. Such a margin of filter performance will prevent a further increase in the content of ammonium and nitrite when new animals are added to the aquarium.
Only unpretentious animals should be used to commission a new aquarium. Animals sensitive to ammonium should only be released into the aquarium after the nitrification processes have been completed. It's best to run the turtles first. They are much less sensitive to ammonium than fish and many invertebrates, in addition, turtles excrete enough organic matter to start the processes of mineralization and nitrification.
Note: in our modern home aquariums, it is recommended to plant snails, plants, armored catfish - corridors, loricari catfish - ancistrus first. These are quite persistent pioneers and are not so expensive.
A good way to start the filter is to gradually increase the number of animals in the aquarium. If there are no unpretentious animals, and the species intended for rearing are sensitive to ammonium, the number of animals should be brought to the maximum gradually. For example, if the ammonium content must be constantly maintained at the level of 0.2 NH4-N/l, the number of animals should be increased slowly, gradually bringing the ammonium content to the required level, planting new individuals no earlier than the nitrifying bacteria bring the ammonium content to 0.2 mg /L or below. This technique is very labor intensive. The first way - creating a reserve filter capacity with the help of unpretentious animals - is faster and more practical.
In cold water, the growth of bacteria and their adaptation are slowed down. Biological purification processes can be accelerated if, before the stabilization of the nitrification processes, the water is heated and thermophilic species are kept in the aquarium. Then warm-water animals can be removed, the water temperature can be lowered, and the same number (and preferably less) by weight of cold-water animals can be put into the aquarium. Sometimes a slight increase in ammonium and nitrite in the water is noted after the introduction of cold water animals, even if the aquarium was previously “balanced”. If the temperature difference is not too great, then the ammonium concentration will even out in a few days, which indicates the adaptation of bacteria to cold. The increase in ammonium content can be minimized by giving the bacteria time to adapt to the lower temperature (96 hours) and then placing cold water animals in the aquarium.
A good method to speed up the “start-up” of a new filter is to transfer the formed population of bacteria from the existing filter to the new aquarium (filter squeeze). Dirt and detritus from a balanced tank can be added to a new aquarium. The soil should be taken from an aquarium where the temperature for several weeks has been the same as in a new aquarium.
Change of water in the aquarium. Excess detritus is undesirable as it makes it difficult for water to flow through the filter. As detritus accumulates in the filter, vertical channels are formed through which water flows with the least resistance, bypassing most of the filter layer. As a result, oxygen starvation begins in the filter, anoxic zones are formed, where the growth of aerobic bacteria is suppressed. For the same reason, it is undesirable to use very fine sand, especially thick filters (“fatty” soil layer).
Removal of excess detritus is carried out by washing the upper layer and transferring the detritus to suspension. It can then be siphoned off at the same time as 10% of the old water is replaced. Rinse the soil carefully. Kawai et al took 1 gr. sand from the surface of the filter and washed with clean sea water. After that, the nitrifying capacity decreased by 40%. With repeated washing, it decreased even more. With intensive washing of another sample, the nitrifying ability decreased by 66%, and subsequent washing - by another 14%. These experiments have shown that a significant part of the nitrifying bacteria inhabits the detritus and, with intensive washing, the bacteria are removed from the filter surface. The filter layer is a permanent system. The soil cannot be removed and washed, as this removes microorganisms along with the detritus. In cases where filter washing is absolutely necessary, this should be done directly in the aquarium using clean water of the same salinity. In freshwater aquariums - appropriately settled tap water.
Nitrification processes are adversely affected by fluctuations in temperature, pH, dissolved oxygen, and salinity. Among these factors, the most significant are changes in temperature and salinity. Less important are pH fluctuations and dissolved oxygen content.
It must be borne in mind that plants and animals, which are usually kept in aquariums, are much more sensitive to changes in the physicochemical characteristics of water than bacteria. In this regard, first of all, the needs of less resistant higher organisms should be taken into account, and only then the bacteria inhabiting the filter, individual cells of which are able to survive in the worst conditions. Thus, although the ranges of environmental parameters given here are narrow for bacteria, they do not prevent the normal development of other aquatic organisms.
Deviations in the parameters of the external environment should be recorded daily, as well as before changing part of the water or replenishing the evaporated water. The oxygen content must be at 100% saturation, this also applies to the added water. This is essential for kept animals, as nitrifying bacteria are not too demanding on the oxygen content. The permissible level of pH fluctuations in brackish and sea water is 8-8.3, in freshwater - 7.1-7.8; The pH of the water added should be close to the pH of the aquarium.
Water temperature has the most noticeable effect on the processes of nitrification, and possibly mineralization. With a decrease in water temperature, one can notice a distinct delay in the transformations of nutrients. An increase in temperature usually increases bacterial activity. Most cold-blooded animals do not tolerate even small temperature fluctuations if they occur very quickly. Temperature fluctuations when replacing part of the water in the aquarium should not exceed 1 degree Celsius per day. This means that the added water must be preheated or cooled. If the aquarium is operated at room temperature, the replacement water should be kept in the same room in a closed container and not used until it is at the same temperature as the water in the aquarium.
Sea water intended for replacement must be of appropriate salinity. Dilute sea water for brackish aquariums in a separate vessel, add fresh water in small portions, taking breaks so that the inhabitants of the aquarium can adapt to it. Preparing water of the required salinity in a separate vessel minimizes possible mistakes and does not disturb the salinity established in the aquarium. Moreover, diluting the sea water reduces the possibility of salinity fluctuations in previously prepared water.
To compensate for evaporation losses in aquariums with any salinity and to replace part of the water in freshwater aquariums, settled tap water is recommended, that is, water that has been kept in an open vessel for three days to remove chlorine. In brackish and marine aquaria, evaporation of water from the surface leads to an increase in salinity, which usually does not have a noticeable effect on most organisms, as it occurs gradually. However, a significant increase in salinity should not be allowed by the time the aquarium is replenished with fresh water. Brackish and marine aquariums should be closed to reduce evaporation of water from the surface and fresh water should be added already at an increase in salinity of 0.2%.