Parameters Of Aquarium Water Hardness, Ph And Other

Parameters Of Aquarium Water Hardness, Ph And Other

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 health 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);

AQUAIUM WATER HARDNESS (hD) – due to the presence of carbonates in water: calcium and magnesium salts: CaCO3 and CaCO3, hydrocarbons Ca (HCO3) 2 and Mg (HCO3) 2, sulfates CaSO4 and MgSO4, chlorides CaCl2 and MgCl2. . Their concentration in aquarium water is GENERAL HARDNESS, which can be divided into TEMPORARY (KH) and CONSTANT (GH).

Temporary water hardness (AH) – This is the concentration of bicarbonate calcium and magnesium. 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 begin to synthesize carbon from the bicarbonate composition, as a result of which temporary water hardness will increase

Permanent aquarium water hardness (GH) – This is the amount of dissolved sulfates, chlorides and some other salts of calcium and magnesium. When such water is boiled, the concentrations of these cations and anions remain virtually unchanged – hence the name “constant hardness”.

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.

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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 – average 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 at the same time will increase 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 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 a tank where water is settled;

– KN hardness is reduced by boiling water in an enamel pot for 1 hour, followed by settling for 24 hours;

– The natural water softeners are fast-growing plants: healer, hornpole, nayas, wallisneria.

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. Take 60-72% of soap, crumbles.

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

3. A soapy crumb (counted in grams) is added to the water, so that it is possible to calculate the amount of soap 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 rapidly disappearing bubbles will 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.

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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 5-6 slightly acidic;

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 you need to increase the pH (strengthen alkalinity) – use baking soda;

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PH measurement of aquarium water:

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 (water rH, water ORP).

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 is charged positively (oxidized), and the other acquires electrons and is charged negatively (restored). As a result, a difference in electrical potentials arises between different-sized substances. Simply put: oxidation is the reaction of the compound of nitrite with oxygen, and reduction – on the contrary, the decomposition of nitrite 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 –significant 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 attic."