clear water

Aquarium clear water

Both professionals and novice aquarists may encounter such a phenomenon as a change in the shade of the water in the aquarium and its clouding. There are many reasons why this happened, but not all of them are actually dangerous. Why does the water in the aquarium sometimes get cloudy and how to deal with this phenomenon?

Causes of cloudy water

For certain reasons, the fluid in the aquarium tank may suddenly change color. It is important to understand that it was the shade that changed – sometimes the water seems cloudy because the front glass has become dirty. We will find out how to make aquarium water clear.

Main reasons

There are two types of reasons, because of which the water changes its color and ceases to be transparent. This may be ordinary mechanical fluid contamination, or biological or biochemical. The water in the indoor pond becomes cloudy for the following main reasons:

  • Incorrect feeding. The fact that the liquid has become less transparent is often due to excess feed. It settles to the bottom, begins to decompose, and the water changes color and begins to have an unpleasant odor.
  • Tightness. If there are too many inhabitants in a small aquarium, it is likely that overpopulation is the cause of the cloudy in the water. It is not necessary to launch an excessive number of fish in a pond.
  • Bad filtering. Often observed in those reservoirs where too many inhabitants live. At the same time, careless aquarists may forget to install a compressor. A well-designed water purification system is the key to a happy life for aquatic life. Otherwise, the water becomes cloudy and stinks.
  • Oversupply of lighting. If the reservoir is lit up excessively, then microalgae begin to multiply actively in it. Due to their growth, the liquid quickly turns green and cloudy.
  • Improper care. Especially the quality of the water changes or when the tank is launched.
  • Badly washed soil. Before putting soil into the aquarium, it is necessary to flush it.
  • The use of peat. Many use natural peat to soften water. But he is able to quickly give clear fish tank water dull brown hue.
  • The presence of wooden products. Remember that due to wooden decorations and decorations, the water in the aquarium can also become brownish-cloudy. This is due to the fact that the tree secretes certain substances.

After changing water

If the aquarium exists not the first day, and because of something you decide to change the water, then sometimes it may become cloudy. This usually happens because all microflora has been removed along with the old fluid.
An aquarium is a separate ecosystem in which biological orders are established for many days. A complete change in water means to restart the aquarium from scratch. If the liquid has been completely drained, then after filling the reservoir it will be populated with useful microorganisms only after some time.
Sometimes the water becomes cloudy after a partial change of water. This procedure serves as an impetus for the imbalance in the ecosystem. Substitution should be done about 10-30% of the liquid of the total volume. Water cloudiness can also cause the improper chemical composition of the water, the rise of debris from the bottom of the reservoir.

After launch

If you have recently taken a great interest in aquariums and acquired a new tank, you should know that fish are put into it after a while. On the first day, put the soil in a container, pour water, after a while plant the plants. Fish colonization occurs at the end of the second week. This period is necessary so that an ecosystem is established in the reservoir.
After starting in the aquarium, a “bacterial outbreak” occurs. Microorganisms begin to multiply in the water, which makes it cloudy. If you change it again, the liquid will again change color. Cloud water passes after 7 days. After that, you can populate the aquarium with fish.
So that the process of establishing balance occurs quickly, you can add a little liquid from another aquarium to aquarium clear water that you want to put in your aquarium. Then the fish will be able to move to the new home after a shorter time.


Water turned white

White water appears in a new aquarium if it was started incorrectly. We talked about this in the previous section.
If the water turned white in the aquarium, not after launch, but where the ecosystem has settled down, then it is important to focus on the feeding regimen. Overfeeding is to blame, and a bacterial outbreak has occurred due to food debris. Also, a sharp population of a large number of new fish can play a role, because of which the established balance will be upset.

The solution to the problem

The solution to the problem will depend directly on its cause. What to do if the water in the aquarium suddenly becomes cloudy?

In the new aquarium

Cloudy water in the aquarium, if new, is a consequence of natural biological processes. Fight this without big care- after a while, the suspension will fall off by itself and your aquarium will have clear water. If you made mistakes, immediately populated the reservoir with fish and fed them, then it is not surprising that the water quickly became cloudy.

If possible, transplant the fish into a second or old aquarium. Put the new one in shade and leave for a few days. Residues of food should be caught.

If the water becomes cloudy after replacing the soil, then you may have poorly cleaned it. It should be washed.

If the reason is wooden decorations, then they need to be removed from the aquarium and soaked for several days in water. The fluid in the new aquarium should be replaced.

In the old aquarium

Correctly fighting cloudy water is not difficult. The main thing is to follow a few recommendations to get rid of it:

  • If the reason for the cloudy water is the overpopulation of the aquarium, then part of the fish should be resettled. Or you can improve the filtration of water. After these measures, everything will return to normal.
  • If the reason is overfeeding, then the fish should have a diet. Do not feed them for a couple of days and drop a bit of water.
  • By the way, in order to ensure that food residues do not accumulate at the bottom, we recommend that you put in a couple of fish species that feed on food residues from the bottom.
  • It is good to have snails that will act as natural “cleaners” of the aquarium. By the way, not only snails but also fish eating them will help to cope with the excessive growth of algae.
  • In the case of cloudy water, look in what condition the filters are. It is possible that they need cleaning or replacement, after which the condition of the water will return to clear.
  • The aquarium standing in the light is shaded – then the microalgae will begin to multiply more slowly, and the turbidity will subside after some time. If the pond is in a dark place, then it must be lightened slightly.
  • If the reason is wooden decorations, then they need to be removed from the aquarium and soaked for several days. Replace the water in the container completely.
  • If none of the above helps to cope with cloudiness, then you can try to use chemicals. Water purifying additives are sold at pet stores.

How to prevent the appearance of cloudy water

In fact, if you follow all the rules for starting and maintaining an aquarium, then there should be no problems with clear water in the aquarium. Of course, they are familiar to experienced aquarists, but it is useful for beginners to learn the basics of caring for the aquarium. The key to the lack of cloudiness is the constant implementation of simple rules.

Right start

Having purchased an aquarium and everything you need, do not rush to launch. Do everything step by step and measuredly. To get started, buy an aquarium, soil, lights, a heater, and a filtration system.
Rinse the soil well with running water and lay it on the bottom of the aquarium installed on a flat surface. Fill in water and turn on the heater at 25 degrees and the filtration system.
At least a week later, you should plant the plants in the ground and turn on the light. The day after that, snails, frogs, newts are introduced into the aquarium. And only a week after that a small amount of fish is launched into the reservoir. Remember that overpopulation is can lead to the appearance of cloudy water.

Proper care

Previously, it was believed that the water in the aquarium should be completely changed several times a year. In fact, this is not worth it! Water changes only in certain cases. The fact is that such dramatic changes are constantly destroying the difficultly established ecosystem. In fact, a complete change of water is the launch of a reservoir from scratch.
It is possible to periodically partially change the water. It must be settled(not water directly put from a tap. Wait at least a day to settle it) also you can pour a bit of water from the aquarium itself.

Water changes are necessary to maintain the balance of chemicals in the norm. But changing more than 30% of the fluid in the aquarium is not worth it – it leads to the shock for aquatic inhabitants.
Usually, the restoration of a balance disturbed as a result of a water change and it lasts a day or two in a large reservoir. And in the small, sometimes the ecosystem is restored in a day or even several hours.
Lighting is also very important, it must be correct. If the tank is located in the dark corner of the room, then even if the day is sunny, it may not have enough light. Take care of artificial lighting. At the same time, remember that excess light is just as dangerous as its lack.
Fish should be fed once a day, and at the same time, they should have a free day once a week. To make it easier, choose one specific day. Don’t use dry food, if fish eat it poorly. After feeding the fish, after 10-15 minutes, make sure that they ate everything, you should get rid of the leftovers. If you follow these rules you will have clear water in aquarium!

If you prefer video explanation to text one I recommend you to watch this one: Be careful this video has SOUND!

Crystal Clear Aquarium Water

Other parameters

The health of the fish, the condition of the plants, and the appearance of the aquarium greatly depend on what properties aquarium water has.

Water is the main component of the aquarium as a biological system, namely, all changes in the aquarium are, first of all, changes in the physicochemical properties of water. Everyone who wants to buy an aquarium needs to have a clear idea of ​​the properties of aquarium water, how various parameters affect the life of fish and plants, and how they can be changed.

You need to understand that in different aquariums there will be water with different indicators, even if you transferred water from one aquarium to another.

Let’s talk about these indicators in more detail.


For most aquarium fish and plants, the optimum water temperature is 25 ° C. It is suitable for most tropical fish originating from the American continent, from Africa, Asia, Australia.

However, among the most common species of aquarium fish, there are two important exceptions.

One exception is cold-blooded fishgoldfish and koi. Regarding the latter, it should be immediately noted that koi are not aquarium fish, they are rather pond fish, if you are going to keep them in the aquarium, then its volume should be at least 500 liters.

For cold-blooded fish, a lower temperature is optimal – about 20 C.

The second major exception is discus. This fish, originating from the American continent, are very fond of the high temperature of aquarium water – about 30 ° C and above. The main conclusion that follows from these facts: you should never plant goldfish or discus with tropical fish. There are many additional reasons for discus to not contain them with fish of other species in the same aquarium.

It is easy to regulate the temperature of aquarium water in winter, spring, and autumn when the air temperature in our apartments is less than 25 degrees. It is enough to buy a reliable aquarium thermostat, which will automatically heat the water to the desired temperature.

However, in the summer, when the air temperature is 30 degrees or more, problems often arise.

First, aquarium plants often do not withstand this temperature and slowly die. Their dead parts begin to rot in the aquarium, which leads to a sharp increase in the content of nitrogen and organic compounds in the water.

The second problem is that with increasing temperature, the solubility of molecular oxygen in water drops significantly, and fish, despite the fact that they can survive a temporary temperature increase, often die from suffocation. Most often, the massive death of fish from suffocation is observed in overpopulated aquariums.

The only really accessible way for most aquarists to prevent fish death, in this case, is to improve aeration of the water at too high a room temperature. Generally speaking, some European companies produce special coolers and fans for aquariums that allow you to constantly maintain the water temperature below room temperature.

However, coolers are quite expensive and are used either in the case of creating a cold-water aquarium for fish of temperate latitudes or in marine aquariums.

Both of these types of aquariums are not suitable for a beginner, and we will not discuss them in detail.

In some apartments and offices, there are air conditioners that allow maintaining the optimum temperature in the room – their use is more preferable than enhanced aeration of water.

Water hardness

Water hardness is associated with the presence of calcium (Ca) and magnesium (Mg) salts in it. These are mainly sulfates, phosphates, chlorides, and bicarbonates (bicarbonates).

The rigidity of aquarium water is usually divided into carbonate (temporary) and non-carbonate (permanent).


The first is due to the presence of bicarbonates and is eliminated by boiling because in this case the bicarbonates turn into an insoluble precipitate and weakly affect stiffness.

Permanent stiffness is associated with the presence of sulfates and phosphates. It is impossible to eliminate it without special equipment (ion exchanger or reverse osmotic filter).

Hardness is usually measured in degrees. The most widespread German scale of degrees of hardness, where 1 ° dH corresponds to a concentration of 10 mg / l CaO (calcium oxide).

To measure stiffness, special reagents are available for sale, the practical application of which is not difficult.

In different regions, water is different.

In practice, this must be taken into account when transporting hydrobionts from one place to another: both fish and plants are very sensitive to a sharp change in water hardness, and they must be gradually transferred from one water to another.

When choosing fish and plants for your aquarium, you must take into account their water hardness requirements. For example, it is completely unacceptable to plant together cichlids from the African lakes of Malawi and Tanganyika, who need hard water, and fish from the Amazon, who need clear soft water.

It is also undesirable to plant a beautiful black fish in aquariums with soft water – common molly (a hybrid of Poecilia latipinna and Poecilia sphenops) and other representatives of the genus Pecilia.

You need to decide what branch of living organisms you want to have in your aquarium in advance and decide what hardness of the water will be in your aquarium and, accordingly, which fish will live with you.

What is bad for fish living in water with unusual stiffness for them?

Fish fauna(aka fish population) in natural reservoirs has been formed for many millions of years.

The way of life of the fish and their physiology were formed during this time in such a way as to fully comply with the conditions of their living in nature.

It is impossible for several years to keep a fish in captivity to make its body rebuild and function well in unusual conditions. If you plant a fish, the ancestors of which have been in soft water for millions of years, in hard aquarium water, then it can survive for some time and can even breed (although these fish very often become infertile). But at the same time, calcium phosphate is deposited in its renal tubules, forms crystals there, the fish weakens and dies.

Those who have encountered a disease that is very unpleasant for a person – urolithiasis, now understand me well. For the rest: believe me, the fish feels very bad with this disease. Therefore, if you have hard water in your water supply, get fish that live in hard water in nature.

If you plant fish from areas with hard water – for example, from Lake Malawi, into soft water, then their water-salt balance is disturbed and ions are washed out of the fish’s body into the aquarium water, where the salt concentration is very low. they decrease the effectiveness of the immune defense, and they die.

It should be noted right away that the diagnosis of these diseases (nephrocalcinosis and disorders of water-salt metabolism) is very difficult. Their negative impact on fish life often occurs indirectly through a weakening of the body as a whole, and some other diseases can become the direct cause of death.

The fish itself will fight for its life to the last, straining all its potassium ions, living with constant pain in the kidneys. Outwardly, you will not notice anything, it may seem to you that these are all empty words and your fish are completely healthy. But I assure you that this is not so, do not torment the animals, just because you like them and you want to admire them at home.

Water acidity video: Be careful this video has SOUND!

Fish Tank Water Hardness Fully Explained: Don't Kill Your Fish!
How can I change the hardness of the water in the aquarium?

Making soft water hard is much easier than making soft water hard.

To increase water hardness, it is recommended to use coral or marble chips as soil, or pieces of marble, limestone (for example, tuff) and other calcium deposits as elements of the interior decor.

Coral chips can also be used as a filler for an external filter. Additionally, add a little evaporated sea salt (obtained without additional processing).

Naturally, all these manipulations require constant monitoring of water parameters, so water must be prepared before you bring the fish home.

To reduce the hardness of the water, you can boil it, you can use ion-exchange resins (however, this is quite an expensive pleasure), or soften the water by passing it through an osmosis filter back.

If you have hard water flowing from a tap, and you really want to engage in fish living in soft water, then it is best for you to get yourself an osmosis filter (the so-called osmosis).

By diluting filtered water with local water, you can get the stiffness you need for your fish.

Also, remember that the world’s leading manufacturers in the field of aquariums produce special drugs to change the hardness of the water.

The only advice that is necessary in this case is to first carefully study the manual for the use of such preparations and avoid sudden changes in water hardness in an aquarium populated by fish.


One of the most important parameters of water that determines the health of fish and plants in an aquarium is its hydrogen indicator – pH.

It is the negative decimal logarithm of the concentration of hydrogen ions (in moles per liter). The pH measurement scale varies from 0 to 14. The average value of 7 – corresponds to a neutral environment, less than 7 – acidic and more than 7 – alkaline environments.


It is important to emphasize that the acidity scale is not linear, the pH indicator is the value of the logarithm.

This means that if we change the pH by only one unit, then in fact the content of hydrogen ions in water changes tenfold.

There is a definite connection between the hardness of water and its acidity. Typically, the higher the hardness of water, the more alkaline it is. And vice versa, the softer the water, the more acidic it is.

For aquariums, it is very important that the temporary or carbonate hardness of water to a large extent determines the buffering properties of aquarium water.

What does this mean? Hydrocarbonates can act as alkalis in aquarium water (therefore, hard water has an alkaline reaction), and when strong alkalis appear in water, hydrocarbons can react as acids.

Due to this property of hydrocarbonates, the acidity of aquarium water remains more or less constant, without changing with small fluctuations in the concentration of substances that oxidize or alkalize water.

That is why the use of boiling water to reduce its hardness is not recommended in aquariums.

Since bicarbonates decompose upon boiling, insoluble calcium and magnesium compounds precipitate, and the buffer properties of water are lost. In order to maintain the buffer properties of aquarium water, it is necessary to place a small piece of marble, tuff, or other special fillers in the aquarium.

In this case, you will create a reserve of calcium compounds, and the hardness of the water is unlikely to seriously change. It is also permissible to add a small amount of drinking soda to the aquarium – sodium bicarbonate.

The hydrogen indicator of aquarium water has a significant impact on the vital activity of aquarium fish and plants.

Water hardness with visual follow: Be careful this video has SOUND!

PH of Aquarium Water? How to Test?
If fish find themselves in water with critical pH values ​​(strongly alkaline or very acidic), then they have chemical burns of gills, mucous membranes, and skin integuments. Serious respiratory and metabolic disturbances occur, and the protective properties of the body are significantly reduced. As a result, fish can die due to a chemical burn or from some other diseases that immediately affect fish with weak immunity.

In plant tissues, pH shifts slow down photosynthesis and other biochemical processes, and at critical values, ​​tissue necrosis and chlorophyll decay are observed.

It must be emphasized that fish and plants can receive severe stress, chemical damage, and significantly weaken even with very short-term fluctuations in the pH level in the aquarium.

Therefore, it is necessary to strive to ensure that the aquarium water has an acidity that is most favorable for aquatic organisms.

When transporting fish, you can’t allow them to be quickly transplanted from one water to another and you cannot drastically change the hydrochemical conditions in the aquarium, for example, change too much water at a time.

Most aquarium fish and plants feel good in water with pH values ​​of 6 to 8, but this is a very rough estimate, not true for all species.

Therefore, before choosing fish and plants in the aquarium, you must make sure that their requirements for the parameters of the aquarium water, including pH, are the same.

As a result of the life of aquatic organisms and the natural development of the aquarium ecosystem, the pH of aquarium water can change.

Changes occur within hours and days, or even months and years. With a sufficiently long period of existence of the aquarium, the accumulation of organic substances and their decomposition products occurs, this leads to a shift in the pH level to the acid side.

The so-called aging of the aquarium occurs, which is characterized not only by a decrease in pH, but also by a drop in the so-called redox potential.

The redox potential (redox potential from the English redox – reduction-oxidation reaction, Eh or Eh) is a measure of the ability of a chemical substance to attach electrons. The redox potential is expressed in millivolts (mV). We will discuss this in more detail below.

Daily fluctuations in the hydrogen index are related to the ratio of the level of respiration of aquatic organisms and the level of plant photosynthesis. Plants, fish, and other aquatic organisms (mollusks, aerobic microorganisms) use oxygen dissolved in water for respiration, while they emit carbon dioxide, and the pH level shifts to the acidic side.

However, during the day, or rather during the period when the lighting of the aquarium is turned on, the plants photosynthesize, absorbing carbon dioxide and releasing oxygen, and a pH shift to the alkaline side occurs.

Daily fluctuations in pH can be very significant, even if there is enough bicarbonate in the aquarium water to act as a buffer.

In order to avoid damage to fish and plants from a high pH level, automatic CO2 supply units are often placed in aquariums. Such installations are controlled using a special device – a pH meter, which constantly measures the pH of the water in the aquarium and regulates the supply of carbon dioxide so that the pH level remains constant.

As a result, two goals are achieved. Firstly, plant photosynthesis is not limited by the lack of carbon dioxide, and secondly, the pH level in the aquarium does not shift to the alkaline side.

From a large number of mineral acids, only phosphoric acid can be used to reduce the pH level in the aquarium. Adding it is possible only dropwise in a highly diluted form.

It is safer to use peat as a filler in an aquarium filter.

Special preparations are available in aquarium shops for lowering and raising the pH level, as well as for maintaining the buffer properties of aquarium water.

Redox potential

This indicator is associated with the level of contamination of the aquarium water with organic substances, as well as with the age of the aquarium.

The succession of an aquarium as a complex biological system (in other words, its natural development) is closely related to the concept of redox potential.

A recently installed aquarium is characterized by high redox potentials; in such an aquarium, very good growth of long-stemmed, small-leaved plants, such as for example cabombas, is observed.

Then, as the aquarium ages, its redox potential decreases slightly, and many species of echinodorus grow actively.

Subsequently, the redox potential becomes very low, and an indicator of this can serve, for example, a good growth of cryptocorynes.

It is possible to maintain the redox potential at a certain level by regularly taking care of the aquarium, cleaning the soil, changing the water, etc.

The use of ultraviolet irradiators and aquarium water ozonizers greatly increases the redox potential.


– Regularly maintain the aquarium, wash the filter media in the filter as needed, properly siphon the soil by removing from the bottom not eaten food residues, rotted plants, and fish waste products. If you neglect your duties, as a result, all this will lead to clouding of the water. Weekly substitution of part of the water reduces the content of nitrogen compounds and helps to stabilize the oxidizability and pH of the water.

For today, that’s all, bye for now, until we meet again.

Next, follow up this article about nitrogen cycles in aquariums to know more about nitrogen cycles.