Water parameters in the aquarium


Aquarium water, parameters: hardness, pH and others


One of the most important components of the aquarium world is water, as the habitat of aquarium fish and plants.

The parameters of the aquarium water, its characteristics directly affect the well-being of your pets and the state of the plants. It is no secret that dirty, muddy water ruins the fish, spoils the appearance of the aquarium, however, the clear water does not always mean that its composition is perfect.

The main parameters and indicators of the quality of aquarium water are:

- Aquarium water hardness (hD);

- Hydrogen indicator of water "Acidity of aquarium water" (pH);

- Redox potential (rH);

AQUARIUM WATER HARDNESS (hD) - due to the presence of soluble calcium and magnesium salts in water. Their concentration in aquarium water is the GENERAL HARDNESS, which can be divided into TEMPORARY - CARBONATE and PERMANENT - NON-CARBONATE.

The temporary hardness of aquarium water (CN) is the concentration of bicarbonate salts of calcium and magnesium, formed from weak, unstable carbonic acid. Such rigidity can vary during the day. For example, in the daytime, aquarium plants during photosynthesis absorb carbon dioxide that accumulates in the water. If carbon dioxide is not enough for consumption by plants, they will start to produce it from the bicarbonate composition, as a result of which the temporary hardness of the water will decrease.

The constant hardness of aquarium water (GH) is the presence of stable calcium and magnesium salts formed from strong acids — hydrochloric, sulfuric, or nitric.

Water hardness is essential for the life of the aquarium world. Firstly, calcium and magnesium salts are used in the construction of the skeleton and have an impact on the construction of the whole fish organism. For different types of aquarium fish, the indicators of water hardness are different and failure to comply with them can lead to a deterioration of the health of the fish, a violation of the function of reproduction and fertilization of eggs.

The total hardness of the aquarium water is measured in German degrees (hD). 1 ° hD is 10 mg of calcium oxide in 1 liter of water.

Aquarium water with hardness parameters:

from 1 to 4 ° hD - is considered very soft;

from 4 to 8 ° hD - is considered soft;

from 8 to 12 ° hD - medium hardness;

from 12 to 30 ° hD - considered to be very tough;

Most aquarium fish feel comfortable with hardness of 3-15 ° hD.

How to change the rigidity of the aquarium water:

1.) Increase stiffness.

- KH hardness can be increased by adding 1 tsp of baking soda to 50 liters, which will increase the performance by 4 ° dKH.

- 2 teaspoons of calcium carbonate to 50 liters of water will increase at the same time KH and GH by 4 degrees.

- Another measure for a smooth / gradual increase in water hardness is scattering and decorating the aquarium with seashells.

2.) Reducing stiffness (everything is more complicated here):

- use / add distilled water, which is sold in stores;

- use / add rain, snow, melt water from the refrigerator (must be clean, without turbidity and impurities).

- filter the water through an osmotic filter;

- filter water through peat (peat is added to the filter) or into the tank, where water is settled;

- the rigidity of the VF is reduced by boiling water in an enamel pot for 1 hour, followed by settling for 24 hours;

- natural water softeners are fast-growing plants: elodey, rogolodnik, nayas, valisneria.

HOW TO MEASURE the overall hardness of aquarium water at home without any specials. equipment and preparations (sample titration with soap solution):

The peculiarity of this method is that 10 mg of calcium oxide in 1 liter of water is neutralized with 0.1 g. clean soap.

1. 60-72% of household soap is taken, crumbled.

2. In a measuring cup (or other measuring vessel), water is poured (distilled, snowy, water melted from the refrigerator) - then distillate.

3. Soap powder (counted in grams) is added to the water so that it is possible to calculate the portion small in the resulting solution.

4. Pour 0.5 liters of the tested aquarium water into another dish and gradually add portions of the soap solution (0.1 gr.), Shake.

At first, gray flakes and quickly disappearing bubbles appear on the surface of the water. Gradually adding portions of the soap solution, we are waiting for all the calcium and magnesium oxide to contact - stable soap bubbles will appear on the surface of the water with a characteristic rainbow overflow.

This experience is over. Now we count the number of consumed soap portions, multiply them by two (the aquarium water was 0.5 liters, not 1 liter.). The resulting number will be the rigidity of the aquarium water in degrees. For example, 5 servings of soap * 2 = 10 ° hD.

With careful experience, the error can be + -1 ° hD.

When obtaining a stiffness result of more than 12 ° hD, the measurement accuracy decreases, it is recommended that the experiment be re-diluted with aquarium water with 50% distillate, double the result.

Hydrogen indicator of water or "aquarium water acidity" (pH of aquarium water).

Determines the neutral, acidic and alkaline reaction of water at a certain concentration of hydrogen ions.

In chemically pure water, electrolytic dissociation occurs - the decomposition of molecules into hydrogen ions (H +) and hydroxyl (OH-), the number of which in it at 25 ° C is always the same and equals 10-7 g * ion / l. Such water is neutral. The negative logarithm of the concentration of hydrogen ions is conventionally used to designate the pH value and in this case is equal to 7. If there are acids in the water (not chemically pure water), the amount of hydrogen ions will be more than hydroxyl - the water becomes acidic with a lower digital pH. Conversely, hydroxyl ions will dominate in alkaline water and the pH will increase.

Aquarium water with pH parameters:

- from 1 to 3 is called / considered strongly acidic;

- from 3-5 sour;

- from 5-6 slightly acidic;

- 7 neutral;

- 7-8 slightly alkaline;

- 10-14 strongly alkaline;

PH parameters can change during the day, due to the variable concentration of carbon dioxide in aquarium water, which in turn is stabilized by constant aeration.

Sharp pH fluctuations are harmful and painful for aquarium fish and plants. Most aquarium fish prefer a pH of 5.5 to 7.5.

HOW TO CHANGE the pH of aquarium water:

- If it is necessary to lower the pH - acidify the water with peat extract (well, or with special preparations from the Pet ShopJ);

- If you need to increase the pH (strengthen alkalinity) - using baking soda;

MEASURING the pH of aquarium water:

1. In many pet stores sold - testers (litmus paper with phenolphthalein). Actually following the instructions on the package and on the scale, you can determine the pH parameters.

2. There are specials. measuring device - PiAshmeter. For home aquariums is not used (expensive, and why not at all). After all, the main thing is not frequent measurement of pH parameters, but conditions of keeping fish and aquarium. In a well-kept, not overcrowded aquarium, not clogged to the top with plants, with aeration - the pH will always be normal and often it is not necessary to measure.

Redox potential (rH of water, ORP of water).

The essence of the redox process in aquarium water is that all substances in it react with each other. In this case, one substance gives up its electrons and charges positively (oxidizes), and the other acquires electrons and charges negatively (being restored). As a result, a difference in electrical potentials arises between different-sized substances. Simply put: oxidation - this is the reaction of nitrite with oxygen, and recovery - on the contrary, the breakdown of nitrites with the release of oxygen.

The maximum oxidative potential of water is 42rH.


rH 40-42 - maximum oxidation (pure oxygen);

rH 35 - strong oxidation;

rH 30 - slight oxidation;

rH 25 - weak oxidation;

rH 20 - weak recovery;

rH 15 - slight recovery;

rH 10 - strong recovery;

rH 5-0 - maximum reduction (pure hydrogen);

Almost all aquarium fish and plants feel comfortable with rH 25-35. Some species prefer narrower parameters of this value.

Measured by rH special gauges.

Increase the rH of water by regularly changing the water, leaving it to clean the aquarium, as well as purging the air and using ozone.


We have learned about the basic parameters of aquarium water, the observance of which will be an absolute guarantee of the health of fish and the beauty of plants.

There are other values ​​/ parameters characterizing aquarium water. However, they are not as significant as hD and pH. To maintain a home aquarium to know and follow them is simply not necessary. As Sherlock Holmes said: "... a sensible person carefully selects what he places in his brain loft."

OPTIMAL PARAMETERS OF AQUAREMOUS WATER (hD of water, pH of water, ORP of water) I ATHERENTLY REACH THE BANAL CARE OF THE AQUARIUM AND FOLLOWING THE RULES OF THE CONTENT OF ITS RESIDENTS: do not make a dormitory out of the aquarium, do not overload it with plants, provide aeration and filtering;

See also:
CHANGE OF WATER IN THE AQUARIUM! WHAT WATER IS NEEDED FOR THE AQUARIUM? How much water should be defended for the aquarium?
Category: Aquarium Articles / EQUIPMENT AND FACILITY AQUARIUM | Views: 23 345 | Date: 5-03-2013, 13:20 | Comments (2) We also recommend reading:
  • - Installation of the aquarium: instructions and useful video
  • - Aquarium and fish for children: tips for parents!
  • - Hylodonellosis treatment
  • - Aquarium at work and in the office
  • - Compatibility of aquarium fish with other fish

Water hardness in the aquarium

Very often, having decided to engage in aquarism, lovers carefully choose a tank for a home pond, think through where to place it, what fish and plants to fill. However, they completely forget about the main and most important component of this whole system - water. As a rule, aquariums are filled with the most readily available water, most often tap water. Very few people think about its parameters. And if it thinks, it is only about whether it is suitable for fish. However, plants are no less demanding of water, although they respond more slowly to its quality.

In this article we will touch on one of the important parameters - rigidity. After all, not least it depends on it, whether the aquarium will become as it is conceived or not.

What is water hardness in an aquarium?

It is considered the second most important parameter of water after acidity. It depends on the possibility of keeping and breeding fish and plants. It affects the remaining properties of water.

This parameter is determined by the presence of certain minerals that are dissolved in water. The overall stiffness consists of two parts:

Permanent (GH). It is paramount, as it determines the softness or hardness of the water and the degree of its suitability for the inhabitants of the aquarium. GH determines the concentration of Ca ++ and Mg ++ ions in water. Boiling leads to the destruction of bicarbonates and precipitation of calcium and magnesium. Stiffness, which persists after boiling, is called constant. It is measured in degrees of hardness. And all the tests are issued in them.

Variable or carbonate (KH). It is determined by the concentration of carbonates CO3- and bicarbonate HCO3- in water.

Aquarium water hardness is normal

The value of water hardness in the life of the inhabitants of the home reservoir is great:

  • magnesium and calcium salts are involved in building the skeleton and bone system of fish;
  • in mollusks and crustaceans, they provide the hardness of the shell or shell;
  • stiffness contributes to the normal functioning and development of the genital organs;
  • it affects the success of the growth and development of plants, etc.

Hardness can be of varying degrees of intensity: 0-4 - very soft, 5-8 - soft, 9-16 - medium hardness, 17-32 - hard, 33 or more - very hard. Tap water, as a rule, has a hardness of not more than 20.

The hardness of the water in the aquarium should be within certain limits, usually this range is 3-15 degrees. It is better if for each specific species the indicators will be close to the natural conditions of the native water bodies.

For example,

  • the snails require hard water, since they sink their shells in soft water;
  • viviparous fish will feel good at 10,
  • neon at 6,
  • Sagittarius and fern at 10-14 degrees, etc. This information can be obtained from the recommendations for the care of one or another species.

You also need to take into account that the inhabitants of the aquarium absorb calcium, so its amount in the water will gradually decrease. Maintaining stiffness at the same level is easier if the soil is pebble or coarse sand. And, of course, regular measurements will be required.

How to determine the hardness of the water in the aquarium?

The main methods are:

Chemical reagent Trilon "B"

This is a very accurate method, but its lack of excessive complexity for people who are not very interested in chemistry, and not everyone wants to acquire additional chemical equipment at home.

TDS meter

He is a conductometer, he is a salimeter. The method is very simple. However, this electronic device measures not the hardness itself, but the electrical conductivity of water, from which it is only indirectly possible to judge hardness.

Test strips

They have been specifically designed to measure the hardness of water in aquariums. Simple and easy to use. There is an option where a reagent is added to a specified volume of water and is judged on the stiffness by the changed color. All calculations are made according to the instructions included in the package. The disadvantage of this method is one - it is difficult to buy such kits, as they are rarely on sale.

Laundry soap

This is the most affordable, cheap and accurate method at home. It is based on the property of soap: it is difficult to dissolve in hard water and gives foam with an excess of calcium and magnesium salts.

How research is conducted:

1. Chop soap (1 gram) and gently pour in a small amount of heated distilled water (sold in car shops).

2. Pour the obtained solution into a glass and add distillate so that it reaches a height of 6 cm for 60% and 7 cm for 72% soap. Each centimeter of this solution contains as much soap as is required to bind salts, the amount of which is 1 ° dH in 1 liter of water.

3. A 1 liter jar half filled with water from an aquarium.

4. Pour the prepared solution slightly into it, stirring constantly. First, flakes appear on the surface, and then a steady lather, which indicates that all the salts in the water are bound.

Score result. Count how many centimeters of the solution was poured into water. 1 cm bound in 0, 5 l of water 2 ° dH of salts. That is, if 4 cm is poured, then the rigidity is 8 degrees, etc. If the entire solution is poured, but there is no foam, then the rigidity is higher than 12 degrees. Then dilute the water for the study with distillate twice, repeat the analysis, multiplying the results by two.

The results may have an error of 1-2 degrees, but this is not critical and will not lead to disease or death of the inhabitants of the aquarium.

If the hardness of the water available to the aquarist does not correspond to that which he needs to maintain aquatic inhabitants, then it can be changed. But it should be done smoothly, so as not to cause stress or other problems in pets.

How to increase the water hardness in the aquarium?

1. Mix the aquarium water with tougher.

2. Boil water for about an hour. It is better to take the enameled ware. Next, cool it and carefully drain the two upper parts of the volume. The lower third, rich in calcium salts, should be poured into the aquarium in portions, controlling the rigidity by measurements.

3. Place in the aquarium pieces of seashells, marble or limestone rocks to increase the overall rigidity by 2-4 degrees. The disadvantage of this method is the inability to control the level of rigidity. It is more preferable to filter the water in the aquarium through a layer of crushed marble, reducing or increasing the amount of water passing through the filter.

4. Add baking soda in the amount of 1 tsp. 50 liters of water to increase variable stiffness (KH) by 4 degrees.

5. Add calcium carbonate at the rate of 2 tsp. 50 liters of water to increase the constant (GH) and variable (KH) hardness by 4 degrees.

6. Add a ten percent solution of Ca chloride (available at the pharmacy) and magnesium sulfate (prepare yourself: dissolve 50 g of the bitter salt, obtaining 750 ml of solution) in the same proportions (1 ml each) in water. Stiffness will increase by about 4 degrees.

7. Pour in magnesia in 25% solution (1 ml per 1 liter of water). This will raise the stiffness by 4 degrees.

How to lower the hardness of the water in the aquarium?

It is much more difficult to do. The methods are as follows:

1. Add distilled, thawed or clear rainwater.

2. Boil water, cool it without stirring, and drain from the surface 2 3. Add this top water to the aquarium.

3. Perform freezing. Pour water into a low bowl, for example, in a basin. Put in the cold. After half freezing, punch the ice, pour the unfrozen water, melt the ice. Add the resulting water to the aquarium.

4. Run water through special filters (osmotic and deionization).

5. Filter the water through peat added to an external or internal filter or placed in a bag in a tank with settled water. Pre-peat for the soil is required to boil. In some spawning peat is used as a soil. The yellow tint of water that it gives can be removed by filtration through activated carbon.

6. You can add a decoction of alder cones.But its hardness decreases slightly and the composition of the water can change, which is not good in all cases.

7. Use Trilon-B and EDTA according to the instructions.

8. Plant elodeyu, egolipu and rogolnik.

Now you know what the hardness of water in an aquarium is, how important it is for its inhabitants, you have an idea how to measure and change it. We hope that this information will help you in creating your dream aquarium. Good luck!

All about tests for the aquarium

Aquarium water testing

In this article we will talk about the practical side of the issue of testing aquarium water.

Why do you need to test the parameters of the aquarium water? What are the tests? Which is better?

So, first, let's enumerate the values ​​that are used to test aquarium water:

NH3 / NH4 is the concentration of ammonia and ammonium in water;

NO2 - nitrite concentration in water;

NO3 - nitrate concentration in water;

pH - "acidity of aquarium water", determines the neutral, acidic and alkaline reaction of water at a certain concentration of hydrogen ions.

GH - constant stiffness;

kH - variable stiffness;

Cl is the concentration of chlorine in water;

CO2 - the concentration of carbon dioxide in the aquarium;

O2 is the oxygen concentration in the aquarium;

Fe is the concentration of iron in the aquarium;

PO4 - phosphate concentration;

Ca is calcium concentration;

Cu is the copper concentration;

Mg is the magnesium concentration;

The values ​​highlighted in bold type are the main - vital indicators, followed by the secondary values, which are tested in a given situation or as needed. For more information about the basic parameters of water, see the article - HERE.

What do aquarium water tests give us?

When dealing with novice aquarists, you encounter a misunderstanding of the importance of this issue. Often you can even hear the phrase: "Well, there are no tests in our city, you are strange, my fish are dying, and you give me - do tests, do tests ... Until then, I was fine and did not test anything."

To reveal the importance of monitoring the parameters of aquarium water, let's turn to the basics of aquarism. Here are her postulates:

1. An aquarium is a complete, almost closed biological system. This is the interconnection of all biological organisms, these are millions of chemical and biological processes that take place every second in the aquarium. In a word, an aquarium is a microcosm in your home!

2. Each hydrobiont (fish, crustaceans, mollusks, plants, bacteria, fungi, other microorganisms), like all living things, prefer certain conditions, certain water parameters under which they are comfortable.

3. Full development in adverse conditions is not possible. In a knowingly “aggressive” environment, any living organism begins to adapt - to matter. In particular, the fish, by the means of an amazing mechanism called immunity, are beginning to “endure” in the hope of “better times.”

4. The immunity of any living organism is not infinite, it is depleted. When this happens, other biological mechanisms are activated - the mechanisms of the withering away or "destroying the weak." The body loses the protective mechanisms that allowed it to resist the pathogenic flora - pathogenic bacteria, fungi and microorganisms penetrate inside and destroy the body.

From the above, we can make a simple conclusion that the root cause of all aquarium troubles, is the inappropriate content of a hydrobiont. It is no secret that all the fish can be divided into softwater (gH below 7), neutral (gH exactly 7) and hard water (gH above 7), "acidic" (pH below 7) and alkaline (pH above 7). About the concentration of poisons such as ammonia, nitrites and nitrates in general can not speak.

When an "aquarium trouble" happens - the fish get sick, the first thing to do is to check the water for compliance with its "standards". Moreover, without "putting water in order" it is impossible to carry out any treatment. Bringing drugs at high concentrations of poisons: NH3 / NH4, NO2, NO3 - you can just kill the fish on the bank, they just will not stand and drugs, and poisons.

Therefore, the primary task of an aquarist is to maintain proper water parameters - this is the key to success! That is why we need aquarium water tests so much!

Does the aforementioned mean that an aquarist at home should deploy a whole laboratory and run as if stung with test strips, cones and test tubes? Of course not. Firstly, because a “healthy aquarium” is always visible - there is no mud, algae, saprophytic mucus, etc. Secondly, having initially tested the water in the aquarium and from the tap, the aquarist already knows the approximate figures that he will always have. Thirdly, water testing is performed as needed - periodically, not daily. Fourth, the packaging of tests involves repeated testing, i.e. having bought once, they will always be at your fingertips.

And the last thing that I would like to emphasize - it is the novice aquarist who needs tests when starting the aquarium! This is due to the fact that in the first month the "ripening of the aquarium" occurs, as a complete biological organism. The unsettled biological system is unstable in the first month and that’s why it needs to be “monitored”, especially for a newcomer!

For more information, see: Nitrogen Cycle brochure, brochure "Aquarium navigator for beginners, issue number 1", "Muddy Aquarium", "Nitrites and nitrates in an aquarium, forum".

What are the tests aquarium water? Which is better to use?

There are the following types of tests:

- tests strips;

- drip tests;

- electronic tests, water testing devices.

Let's look at them on the example of tests from the company Tetra.

Aquarium test strips

Tests of the strip determine the basic parameters of water: nitrites, nitrates, hardness, acidity and chlorine. What is their plus - ease of use, you just need to lower the test strip into the water, and then check the color of the "indicators" with the attached scale and get the results. In addition, they are relatively inexpensive and often in pet stores you can buy them individually. In what a minus - they are not accurate, the test strips give only an approximate value, that is, you will not get exact numbers. In addition, it is worth noting that ammonia test strips do not determine, and it is important, the sensitivity of the test strips to nitrites from 1 mg / l, while the maximum permissible concentration of NO2 is 0.2 mg / l, that is, there is no gradation from 0 to 1. In fairness, it is worth saying that Tetra has separate test strips for ammonia.

Test strips can be used to determine the status of the aquarium as a whole. You should not discount them, but at the same time you need to understand their conventionality.

Aquarium water drop tests

Are the most accurate. The essence of their use is similar to test strips, only in this case the determination of a parameter occurs by the color of the liquid, by comparing it with the color of the scale. Each such test is given detailed instructions, so we will not go into details of all the manipulations that are carried out when testing aquarium water through drip tests. Note that these tests are the most popular and acceptable - a combination of price and quality.

Drip tests for a particular water parameter are sold both individually and in sets, which gives the aquarist options. But, probably, the dream of every aquarist is a suitcase-laboratory of aquarium tests. For example, Tetra WaterTest Set Plus. This is where there is a roam aquarium shower!

Aquarium water electronic tests

There are a number of devices that determine a particular parameter of water. Some of them are expensive and their acquisition is not appropriate. But there are also cheap ones, for example, an electronic pH tester, which can be purchased at any Chinese store (ali-express). The device is an electronic indicator, similar in shape and size to the "marker". To use it, you only need to insert the batteries, calibrate it (periodically, using indicator liquid) and then simply lower the device into the glass with aquarium water. Digital scoreboard will give the result.

Summing up, we recommend that a beginner aquarist acquire drop tests, primarily tests for ammonia products: NH3 / NH4, NO2, NO3, and secondly for pH and GH.

The remaining tests are also important, but their need for several reasons is less important.

Cl - the concentration of chlorine in water should be zero. Its minimum content in water is destructive. This is partly why we defend water so that chlorine from tap water evaporates.

CO2 - the concentration of carbon dioxide in the aquarium. The parameter that is important for aquariums with a large number of plants is for herbalists. CO2 is a fertilizer, plants take carbon (C) from it in the process of photosynthesis, which is an important component in building the plant's body. Speaking of CO2, it is worth mentioning such a "test in time" as a drop checker, by means of which the sufficiency of carbon dioxide in the aquarium with plants is determined. See more details - HERE.

O2 - The estimated concentration of oxygen in the aquarium should be 0.5 mg / l. The value is approximate, because all the aquariums are different. The lack of a sufficient concentration of oxygen in water can be primarily determined by fish. They begin to greedily swallow air near the surface of the water and breathe heavily, it is impossible not to notice. In general, it can be said that O2 is an important indicator and there is no overabundance of oxygen in the aquarium, often the wrong actions of a beginner lead to the opposite - to his absence. See the article for more details. "Aeration of the aquarium".

Fe - A test for the concentration of iron in an aquarium, often used by aquarists in herbalists. Iron is a micro fertilizer for plants, its overdose or shortage has certain negative consequences.

Po4 - phosphate concentration, also measured in herbalists. Since in such aquariums the ratio of pH and NO3 is important. In plant-free aquariums, the phosphate content should tend to zero;

Ca - calcium concentration, often measured in saltwater aquariums;

Cu - copper concentration. Poison for invertebrates and sensitive fish, but also a micro fertilizer for aquarium plants;

By the way, if in your city there are certain problems with the assortment of tests for an aquarium, you can order and buy them in the online store. For example, our partner store - here. All forum users discount 3%.

Video about testing aquarium water