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How to make a water change in the aquarium

maintenance, care, compatibility

How and how much to change the water in the aquarium, the frequency of water changes

How to change the water in the aquarium?

In this article we will discuss a fairly simple, but at the same time, a difficult question regarding the change of water in the aquarium. It is simple because there is no need to replace water in the aquarium.

However, there are a lot of nuances and certain specifics that you need to know on this issue. The matter is further complicated by the lack of complete, comprehensive information on the Internet.

As a rule, information about the change of water in an aquarium is either compressed, or one-sided, or only a certain part is covered.

No exception was our site. Here, for example, article Boiled, melted or distilled water for aquarium.

It seems the article is good, but narrow and concise.

So let’s fix this defect. We will consider the question “How to change the water in an aquarium?” As fully as possible and that, in turn, will enable us to make changing water as simple and effective as possible.

For convenience, let’s break down the article into the following sections:








Many novice aquarists are faced with different opinions about the need to change the aquarium water. Often on the forums or from friends you can hear the phrase: “That I do not change the water at all and …. all OK “or” I rarely, rarely … and also all OK. “

Here that, at the beginner and there is a stupor! How so?

I’ve decorated the entire balcony with buckets, how do I carry a water carrier from the bathroom to the aquarium, but it turns out that this is “monkey labor” !? Without tormenting for a long time, I will answer you – do not listen to these “uncles and aunts”!


And the thing is this! In the process of vital activity of all aquatic aquatic organisms (inhabitants), the aquarium itself, or rather, the water becomes clogged.

For example, an excess of food, fish feces, dead leaves of plants and other organic matter. All this “dirt” turns into the most terrible poison – ammonia, which is destructive for all living things in an aquarium.

Further, nitrifying bacteria that are in the water, the filter and the soil “decompose” ammonia to nitrite (poison), then nitrates (“weak” poison), and then the remains turn into a gaseous state and leave the water.

So, no matter how many useful nitrifying bacteria are in the aquarium of colonies, no matter how many live plants are in the aquarium, which also partially absorb ammonia, no matter how powerful the filters are … no matter, the above poisons tend to accumulate. And you can bring them ONLY REGULAR REPLACEMENT OF WATER TO CLEAN.

What happens in an aquarium for those who do not change the water for a long time? Many aquarium fish tend to adapt and live in the worst conditions – get used to the poisons.

However, this function of “survival in any conditions” is not eternal. In fish, irreversible changes occur in the internal organs, mucous membranes and gills. Fish weaken, their immunity falls.

And the “Doomsday” comes when an outbreak of a bacterial, fungal or infusorian attack occurs … not many survive!

In total, the change of aquarium water is one of the most important ways to maintain “health in the aquarium”, one cannot do without it. Laziness in this matter is a fatal mistake!



There is such a non-contagious sore in fish, called Gas embolism. In a nutshell – this is the entry of small air bubbles into the blood vessels and blood of fish. As a result, there is a blockage of blood vessels.

Fishes begin to swim sideways, the behavior becomes alarming, fearful. The fins and the whole body begin to tremble convulsively.

The movement of the gill covers slows down, and then completely stops … further death!

A frequent cause of gas emboli is inadequate settled water for an aquarium. The fact is that tap water (tap water) is excessively saturated with air bubbles that are so small that they are not even visible to the human eye.

Just imagine how much water “poured through the pipes” until it reached your tap!

Thus, filling the tap water in an aquarium with fish – YOU ARE VERY RISK. Yes, in practice, everything can do, but this is a game of Russian roulette.

What happens to water, if it is defended? What happens is that small bubbles gradually merge and come out of the water.

Water saturation by air decreases, the risks are reduced to zero.

In addition, it is worth noting that in the process of settling water for the aquarium, heavy and harmful compounds, for example, chlorine as sediment at the bottom of the container and film on the surface of the water, settle.


Everything is simple and should not cause much difficulty. The water in the aquarium should settle in a container with a wide neck: a bucket, a basin, an enamel saucepan.

You understand that in a bottle with a narrow neck, excess air goes out poorly. Container for sludge should not be metallic, rusty or made of toxic substances or paints.

Plastic buckets, perhaps the best and easiest option for defending aquarium water.

About the time. The longer the water settles, the better! I personally defend the water for 7 days – this is convenient and coincides with my Sunday schedule for changing the water in the aquarium.

In general, such terms of water settling 1-14 days roam the Internet.


But this is really a problematic issue for owners of large aquariums and not large apartments! How to defend 50, and then 100 liters of water?

If this is a new aquarium and the first launch of the aquarium is made, you can immediately fill in the aquarium with tap water, defend it and at the same time add air conditioners to improve the quality of water.

If water is needed for replacement, then our first glance is the only rational option is to purchase construction containers (plastic buckets for mixing mixtures) for 50, 100 liters.

Other ways to prepare aquarium water in the first place include: boiling, freezing water, as well as its purchase of water in the store. See more about this. HERE.

Also, aquarium water can be prepared using special air conditioners such as: Tetra AquaSafe, AMMO-LOC, Sera aqutan and others.

Here is a video about one of them:


Almost in all books, on all sites, they write standardly what needs to be changed weekly? part of the water from the total volume of the aquarium. This is a generally accepted norm, BUT NOT DOGMA.

Here, look, please statistics of the survey, which is conducted on our site.

How often do you change the aquarium water to fresh?

As you can see, everyone changes the water in different ways and the weekly replacement of aquarium water is not a dogma! Why?

It’s very simple – everyone has different aquariums, different fish, plants, and so on. For example, there are fish that love the “old” water and the frequent change of water only annoys them (the family of labyrinth fish).

The abundance of living plants, also reduces pollution in the aquarium. In the end, someone has a large aquarium, someone has a small, someone has a big fish, and someone has a small one.

All this individual specificity of the content of fish excludes the concept dogma number and frequency of substitution of aquarium water. And there is only one advice – you should adapt yourself and you should come to the conclusion about how often and how much water you need to change in your aquarium.

In this case, you must take into account the volume of the reservoir, the population of the aquarium, the individual characteristics of the fish, the presence or number of plants, the filter power, the presence of ion exchange resins in the filter, and so on.


Finally, I want to give attention to the beginner aquarists, that it is only necessary to change the aquarium water after cleaning the aquarium, and not before.

That is, first we:
– clean the filter and other equipment;
– wipe the walls of the aquarium;
– we thin and cut the plants;
– siphon soil;
– perform other manipulations and permutations;
– and only then we replace part of the water with fresh one;

If you have any questions, any comments on the article, please leave them in the comments – we will discuss.

Novice aquarists suggest that replacing water in an aquarium is accompanied by some kind of disorder spilled by water around the house and a huge waste of time. In fact, all this is not so.

Changing the water in an aquarium is a simple process that does not take you long. In order to perform this simple procedure, you just need to have the knowledge and, of course, to acquire all the necessary tools that will be your permanent assistants. So let’s start with what a person should know when starting the water replacement procedure.

First of all, this is what all aquariums are divided into large and small. Those aquariums that do not exceed two hundred liters in their capacity are considered small, and those that exceed two hundred liters in volume are the second type.

Let’s start with the replacement of aquarium water in small objects.

  • ordinary bucket
  • crane, preferably ball
  • siphon, but always with a pear
  • hose, the size of which is 1-1.5 meters

In order to perform the water change for the first time, you need to connect the siphon to the hose. This procedure is necessary to clean the soil in the aquarium. If there is no siphon, use the bottle, after cutting the bottom of it.

With a pear or mouth, draw water until the entire hose is filled. Then open the tap and pour water into the bucket.

This procedure can be repeated as many times as you need to replace. By the time such a procedure takes no more than fifteen minutes, but if a bucket without a spout, it will be a little more. When you do this for the first time, the skill will not be there yet, respectively, the time period may also increase.

But this is only at the beginning, and then the whole procedure will take a little time. Aquarists know that changing the water in a large aquarium is easier than in a small one.

Just need a longer hose so that it reaches the bathroom and then the bucket is no longer needed. By the way, for a large aquarium, you can use the nozzle, which easily connects to the faucet and fresh water will easily flow.

If the water has managed to settle, then, accordingly, you will need a pump that helps to pump fluid into the aquarium.

  • The first two months should not replace the fluid at all
  • In the subsequent time, replace only 20 percent of the water.
  • Partially change the fluid once a month
  • In an aquarium that is over a year old, the liquid must be changed at least once every two weeks.
  • Full replacement of the fluid is made only in emergency cases.

Compliance with these rules will preserve the necessary environment for the fish and will not allow them to die. It is impossible to break these rules, otherwise your fish will be doomed.

But it is necessary not only to change the water, but also to clean the walls of the aquarium and at the same time not forget about the soil and algae.

Changing the aquarium water is easy, but you should not forget about the inhabitants. Fish every time there is a change of water, are under stress.

Therefore, every week it is better to perform the procedures to which they gradually become accustomed and already perceive them calmly over time. This applies to any type of aquarium, regardless of size: small or large. If you keep a constant eye on the aquarium, you often do not have to change the water.

Do not forget to take care of the general condition of the fish dwelling. So, it is worth changing the algae that grow in the aquarium, because they pollute the walls.

It takes care of other plants that need not only to be changed as needed, but also to cut the leaves. To add additional water, but how much it can be added, is decided in each case separately.

Do not forget about the gravel, which is also cleaned or changed. You can use a filter for water purification, but often this does not affect the conditions of the aquarium. But the main thing is not only to change the water, but to ensure that the lid in the aquarium is always closed.

Then the water will not be so quickly polluted and it will not have to be changed frequently.

Video on how to replace the water and clean the aquarium:

Now, when it is clear that water replacement is important, you need to understand that too much, as too little water change is bad. Although in general, water change is needed, it is necessary to do it carefully, as any abrupt changes in the closed world of the aquarium harm it.

Too much water replaced at one time may be harmful. Why?

When 50% or more of the water is changed to a new one, this significantly shifts the characteristics in the aquarium — rigidity, pH, even the temperature changes significantly. As a result – shock for fish, useful bacteria that live in the filter can die, tender plants lose leaves.

In addition, the quality of tap water leaves much to be desired, namely, it is used in most cases. It has elevated levels of minerals, nitrates and chemicals for water treatment (the same chlorine).

All this is extremely negative impact on the inhabitants of the aquarium.

Replacing water only partially (no more than 30% at a time), and not half at once, you make only small changes in the established balance. Harmful substances come in limited quantities and are utilized by bacteria.

A large replacement, on the contrary, maintains a dangerous level and significantly upsets the balance.

If you have an open aquarium, you will notice that a large amount of water evaporates. At the same time, only pure water evaporates, and all that it contains remains in the aquarium. The level of substances in the water is constantly increasing, which means that in an open aquarium, the process of accumulation of harmful substances goes even faster.

Therefore, in open aquariums, regular water changes are even more important.

Replacing the water in the aquarium is an obligatory process for its maintenance. There are partial substitution and complete replacement of water.

Partial substitution in a freshwater aquarium is necessary to maintain the balance of the formed environment due to the fact that it evaporates and changes its composition. However, before changing the water in the aquarium, time should pass from the day of its launch: at least 2 months.

The frequency of partial replacement procedures is once every 1-2 weeks. Replace recommended 1/5 of the total.

Beginner aquarists face the question: how much to defend the water for the aquarium? If tap water does not contain chlorine and phosphates, then it can and not be defended.

Check for the presence of harmful substances necessary tests. If these compounds are in tap water, then you can defend it for day 3. Also, the preparation of water for the aquarium can be carried out using special compositions to change the chemical composition of the water.

With a sufficiently large volume of the aquarium (more than 150 liters) without special preparation, you can replace up to 20% of water in it.

Deciding what kind of water is needed for an aquarium when carrying out a partial substitution, should be guided by the capriciousness of the species of fish and plants that inhabit it.

Muddy aquarium: from what and why the water becomes cloudy, what to do

Preparations eliminating mechanical turbidity in an aquarium

If the clouding of a young aquarium is forgivable to an aquarist, then dregs in the old pond are his sin! Violation of the biobalance in well-established water bodies is often due to oversight, due to the lack of basic care, due to ignorance or unwillingness to know what is happening in the aquarium.

The exculpatory causes of the clouding of the old aquarium are “whiteness after the treatment of fish”, that is, when aquarium chemistry and preparations were used in the aquarium. Like any “medicine” aquarium chemistry has side effects, in particular the violation of biological equilibrium.
What happens in the old aquarium? Why does the water grow cloudy in it?
And almost the same thing happens as in a young aquarium. But, if I may say so, in regressive order.
To make it even clearer to you, let’s break the aquarium biological chain into links. NITROGEN CYCLE is as follows.
(remnants of dead organics, fish food, feces, etc.)
decompose under the action of bacteria in

(the strongest poison, destructive for all living things)
under the action of another group of bacteria is decomposed into

(less dangerous, but also poisons)
further decompose to

and out of the aquarium water
As you understand, this process is multistage and has its own nuances.
For those that want to study it in more detail, I recommend to go to the forum thread NITRITES AND NITRATES IN THE AQUARIUM. And now imagine what will happen in the old aquarium, if one of the links, for one reason or another, falls out?

That’s right – dregs! Sorry for the tautology))) Unlike the dregs in a young aquarium, the turbidity in the old aquarium not only spoils the appearance of the aquarium, but is also very dangerous. The following happens: under the influence of non-excreting poisons, the fish’s immunity weakens, their protective mechanisms weaken and become unable to resist the “harmful” – pathogenic bacteria and fungi (which are always in the water).

As a result, the fish gets sick and if you do not conduct treatment in time, the fish dies. Thus, we can conclude that the violation of biological balance is the primary cause of the death of aquarium fish. In fairness, it should be said that the saturation of aquarium water with excess ammonia, nitrite and nitrate – can occur without turbidity of the aquarium water.

What is even worse, because the enemy is invisible.


or how to set up biobalance
First of all, you need to make regular cleaning in the aquarium, do not overfeed the fish. Remember that only the constant and correct replacement of aquarium water to fresh water is an effective way to get rid of poisons.
ATTENTION: To replace the water in a young aquarium, in order to get rid of turbidity is not necessary. In the first month, the water in a young aquarium generally needs to be tried less often and in smaller volumes.

Water should “infuse.”
Drugs that eliminate the biological clouding of the aquarium – preparations setting biobalance:
Almost all aquarium brands in their arsenal have a line of products that customize the biological balance.
The essence of these drugs can be divided into those that:
– neutralize poisons (nitrites and nitrates);
– promote the growth of colonies of beneficial denitrifying bacteria or are a ready concentrate of these bacteria.
To achieve the maximum effect, you should use these drugs in a complex. Especially with a flash of nitrite and nitrate.
Preparations that neutralize nitrites and nitrates Zeolite is an ion exchanger, in fact, as well as aquarium coal is an absorbent. But, unlike coal, which is not able to “tighten” nitrites and nitrates, zeolite copes with it perfectly.

Zeolite is used not only in aquarism, it is widely used in other areas of human life. Therefore, it can even be bought by weight.
Zeolites are a large group of similar in composition and properties of minerals, aqueous aluminosilicates of calcium and sodium from the subclass of frame silicates, with glass or pearlescent gloss, known for their ability to give and reabsorb water, depending on temperature and humidity. Another important property of zeolites is the ability to ion exchange – they are able to selectively release and reabsorb various substances, as well as exchange cations.
Aquarium preparations containing zeolite.

Fluval zeo-carb – filler for filters zeolite + activated carbon.
This is a combination of Fluval activated carbon and Fluval Ammonia Remover. Working together, these highly effective means of active filtration, which eliminate pollution, odors and color, and at the same time, remove toxic ammonia:
– Protects aquarium from toxic ammonia.
– At the same time, coal adsorbs waste products, dyes and drugs from water.
-Reduces the phosphate content in water.
The combination of the two products frees up space in your filter for other types of filtering.
Aquael ZeoMAX Plus – zeolite in the form of small crumb, removes ammonia and phosphates, stabilizes pH.
Due to its chemical structure, it provides excellent absorption of organic pollutants, nitrogenous compounds and phosphates that are toxic to fish, which are a consequence of the metabolism of aquarium inhabitants.
Zeolite should not be left in the filter for more than one month.

For more information about the advantages and disadvantages of zeolite, see the forum thread “Nitrites and nitrates”, namely HERE.
The drug acting at the chemical level.

Sera toxivec – a drug that at the chemical level instantly eliminates NO2NO3. Since this is chemistry, it is recommended to use it as a preventive measure and once.
Immediately removes hazardous contaminants, life-threatening fish and filter bacteria, from aquarium water. Equal effectiveness against different types of pollutants makes this tool especially valuable.
Sera Toxivec instantly eliminates ammonia / ammonia and nitrites. Because of this, it prevents their transition into nitrates and helps prevent the growth of irritating algae.
In addition, Sera Тoxivec eliminates aggressive chlorine from tap water. Also effective as a disinfectant disinfectant and medication remover.
At the same time, it is capable of even more: it binds toxic heavy metals such as copper, zinc, lead, and even mercury. Therefore, these pollutants can not harm the fish and beneficial bacteria in the biofilter.

Due to this, the frequency of water changes can be reduced.
If necessary, for example, with particularly high levels of contamination, an increase in the applied dose of the agent is allowed. Repeated depositing is allowed in one or two hours.
Drugs that promote the growth of beneficial colonies
bacteria or are ready concentrate bacteria
Tetra Bactozym – This conditioner, accelerating the process of stabilization of biological equilibrium, in the filter and aquarium. Suitable for fresh and sea water.
Tetra Bactozym accelerates the conversion of nitrites to nitrates and contains a concentrate of enzymes and substances that contribute to the development of beneficial aquarium microflora. It makes water crystal clear and provides enzymatic decomposition of dissolved organics.

The use of an air conditioner reduces the damage done to the beneficial microflora when changing water and washing the filters, and restores microorganisms that are weakened or damaged by the use of medicines.
We draw your attention to the fact that biostarters contain various types of cultures of bacteria and enzymes. Too high or low temperatures reduce their effectiveness.
Tetra NitranMinus Perls (granules) – for reliable reduction of nitrate in water. The drug eliminates the nutritional element necessary for the development of algae, which allows for a long time to improve water quality, reducing, thereby, the need for care of the aquarium.
– lowering the level of nitrates by 12 months by biological means.
– algae growth is significantly inhibited.
– just buried in the ground.

Tetra NitrateMinus (liquid conditioner) – biological reduction of nitrates, calculated for 12 months. Improves water quality.

Interferes with formation and growth of seaweed (duckweed). Designed for all types of marine and freshwater aquariums.
Convenient dosing: 2.5 ml of new liquid NitrateMinus for every 10 liters of water, once a week.
Like NitrateMinus in granules (Pearls), liquid NitrateMinus facilitates the processing of nitrates into nitrogen and lowers carbonate hardness. A decrease in nitrates by 60 mg / l leads to an increase in carbonate hardness of approximately 3 KH. With regular use of the drug after replacing water, the pH of the water stabilizes and the risk of falling acidity decreases.
Fully compatible, NitrateMinus is based on biological processes in an aquarium and is completely safe for fish. It combines perfectly with TetraAqua EasyBalance and other Tetra products.
Sera bio nitrivec (Sera bio nitrivek) – preparation for quick start aquarium. Special blend of various high-quality cleansing bacteria for aquariums. Sera nitrivek prevents the accumulation of ammonium and nitrite.

The use of Sera nitrivek makes it possible to place the fish in the newly created aquarium already 24 hours after application. When entering the water bacteria
begin to act immediately. The resulting effect is stored in
For a long time, giving a crystal water aquarium water.
There are other drugs of identical orientation. I recommend sharing Tetra Bactozym and Tetra NitranMinus Perls.
And when using NO2NO3 flashes, use zeolite.

How else can you achieve a “good biobalance”?

– Biological equilibrium is more stable if live aquarium plants are present in the aquarium. Plants partially absorb the decay elements of living organics and thereby reduce their concentration. The more aquarium plants, the better.

I recommend to read the article. AQUARIUM PLANTS ALL FOR BEGINNERS.
– Aquarium snails and fish “orderlies” will help you in cleaning the aquarium. “Squad” of the same coil snails copes with dying leaves and organic matter. Fish nurses also help in this matter. The majority of aquarium catfish can be attributed to them: corridors, antsistrusy, girinoheiliusy, aquatic sequences, thoracacums, and many others.
– It is advisable to use multistage filtration of aquarium water. And also use other methods that improve water quality, for example, phyto filtration.

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