▷ PH value in the aquarium | Information and variants to lower the PH value

Here you will find information about the PH value in the aquarium, its importance and various ways to lower / change it.

Diagram for standardizing the PH value:

© Norbert Heidbüchel

PH basics

© underdogstudios Fotolia.com

The pH value indicates the ratio of the acids and bases dissolved in the water to one another. To be precise, the pH value indicates the concentration of hydrogen ions H+.

H+ ions make the water acidic. The more H+ ions, the more acidic the water and the lower the pH. For water, the multiplication of H+ ions and OH– ions always results in a constantly equal value. x = constant ~ 10-14.

Water with a pH of 7 is called neutral. At pH 7, the concentration of H+ ions is exactly equal to the concentration of OH– ions. Higher pH water is referred to as basic or alkaline and lower pH water is referred to as acidic water.

The pH is a logarithmic value. Water with a pH value of 7 therefore contains ten times more H+ ions and ten times fewer OH- ions than water with a pH value of 8.

It is log() + log() ~ -14. A pH of 6 means about 10-6 H+ ions and about 10-8 OH- ions. That means there are a hundred times more H+ ions than OH– ions in the water.

Theoretically, distilled water, osmosis water or deionized water is also neutral. Because the water quickly absorbs carbon dioxide from the air, the three-way relationship can quickly result in a pH of around 5.5.

Fish and plants can be damaged if the pH value in the aquarium differs too much from the usual values ​​from the waters of origin. Most fish are naturally adapted to keeping the pH within certain ranges. Some species of fish survive and spawn only in water that is within a narrow pH range, while other species do not require such specific pH levels.

Most bacteria require neutral pH values ​​between 6.5 and 7.5. Their metabolism works optimally at these levels and they multiply well. Lower or higher pH values ​​reduce the speed of the bacteria’s metabolism. Therefore z. B. in extremely acidic waters, z. B. in moors, deceased creatures are mummified, which would be quickly decomposed by bacterial processes at other pH values.

Home waters with neutral water with pH values ​​between 6.5 and 7.5:
Most species of fish and plants can be successfully kept in neutral water.

Acidic water with pH values ​​between 5.0 and 6.5:
Fish from such waters are very sensitive to bacterial diseases and ammonia poisoning. Biological filtration is less effective. Heavy metals are more toxic in soft water.

Solutions:
The pH in the aquarium should be low. Fewer fish should be kept than with neutral values, ie more water volume should be available per unit weight of fish. A larger filter should be used or more plants should be cultivated for water purification. Osmosis water should be used. Water conditioners and dissolved organics can help prevent heavy metal poisoning.

Alkaline water with pH values ​​between 7.5 and 9.0:
Fish from these waters can be very sensitive to nitrite poisoning. Biological filtration is less effective than neutral water but more effective than soft water.

Solutions:
The pH in the aquarium should be high. Fewer fish should be kept than with neutral values, ie more water volume should be available per unit weight of fish. Care must be taken to ensure that the nitrite and ammonia content does not become too high. This requires good biological filtration and water changes. Plants help keep ammonia levels down. Some salt can help prevent nitrite poisoning. Wood and roots should not be used for decoration because they could lower the pH.

Strong fluctuations in pH are dangerous.

It can be more important to avoid large pH fluctuations than to reach a certain pH level. Sudden changes in pH will harm most of the creatures in the aquarium. The carbonate hardness buffers the pH value. The higher the carbonate hardness, the more stable the pH value. Therefore changes in the CO2 content, e.g. B. by CO2 fertilization and photosynthesis of the plants, with soft water more on the pH than with high carbonate hardness.

The pH value in the aquarium is influenced by various factors.

An important factor influencing the pH value is the carbon dioxide content in the water. Because carbon dioxide in water is partially converted into carbonic acid H2CO3, the pH value decreases the more carbon dioxide there is in the water.

When carbon dioxide is removed from the water, e.g. .B. by aerating the water, carbonic acid is converted into carbon dioxide and the pH rises.

The pH value is a logarithmic variable, ie a change by a factor of 1 changes the acid concentration by a factor of 10. The effects of a pH change on the aquarium inhabitants can be correspondingly dramatic.

Change in pH

Ideal accessory for the PH value in the aquarium:

No products found.

There are several methods for lowering pH:

Can the pH be adjusted with lemon extract?

In addition to citric acid, lemon extract contains organic substances. In chemistry, organic acids such as citrate, acetate and oxalate are used to set specific pH values ​​because they form good buffer systems. In contrast to the aquarium, however, there are no filter bacteria in the test tubes. Bacteria process the organic substances in the so-called citric acid cycle, using oxygen to generate energy. Citric acid can therefore lead to bacterial blooms and lack of oxygen. Nitrate filters are often lined with acetic acid for the same reason.

Since the carbonate hardness is not completely destroyed when citric acid is used, the citric acid buffer system also overlays the carbonate hardness-carbon dioxide buffer system. With high carbonate hardness, i.e. high buffer capacity, a correspondingly large amount of citrate is then required. The more citrate the bacteria have available, the more oxygen they use. Since citrate has to be constantly replenished, there is a permanent bacterial bloom. Bacterial blooms lead z. B. to a high germ load for the fish.

Humic acids are difficult for bacteria to break down. They consist practically of the indigestible residues of organic substances that remain after mineralization. Since the buffer capacity is similar to that of citrates, low pH values ​​can also be set with humic acids. In addition, humic acids have other positive properties, e.g. B. they have an antibacterial and antifungal effect. However, the carbonate hardness-carbon dioxide buffer system must not dominate here either, ie the effect only occurs with low carbonate hardness.

Lower PH value

Lower the pH with CO2

TheDigitalArtist / Pixabay

If the pH value only needs to be lowered slightly, a CO2 system can be used.

At the same time, the plants are fertilized with it. In the case of stronger reductions, however, too much CO2 has to be fed into the water.

The fish can then be damaged, e.g. B. Gill burns.

For this reason, CO2 is not suitable for significantly reducing the pH value in the case of high carbonate hardness and a high pH value.

Lower the pH with peat

Bernswael / Pixabay

Peat can lower the pH somewhat. Peat acts as a weakly acidic cation exchanger. The capacity is about 0.1 mol/liter monovalent ions.

The aquarium water is discolored yellow-brown by peat. Many fish come from waters that are also colored like this in nature. Peat also has an antibacterial effect. The color darkens the light. Light-hungry plants can therefore suffer from a lack of light.

Peat also lowers carbonate hardness. The humic acids contained in peat destroy the carbonate hardness, like other acids.

If the carbonate hardness is high, peat is unsuitable. The carbonate hardness is reduced by a maximum of 2 to 3°. It would take far too much peat to significantly reduce carbonate hardness or pH.

The peat has to be renewed after approx. 14 days, otherwise it will be microbiologically degraded and the water will be polluted with the decomposition products.

Lower the pH with oak extract

Most oak extracts consist of hydrochloric or phosphoric acid.

Lower the pH with acids

Acids destroy the carbonate hardness. A reduction in carbonate hardness leads to a lower pH value if the carbon dioxide content of the water remains the same. Mineral acids, e.g. B. hydrochloric acid, are inexpensive, but can cause chemical burns, etc. in high concentrations. Organic acids, e.g. B. citric acid, are consumed by bacteria as food and can lead to bacterial blooms. Organic acids have a relatively short-lived effect due to degradation by bacteria. With repeated use, the effect becomes less and less because the number of bacteria increases.

Improper use of acids can easily lead to an acid crash. When using hydrochloric acid, the conductance increases noticeably. The water must be treated outside the aquarium. Otherwise strong acid concentrations can occur in the aquarium. The pH value in the aquarium can also drop too quickly and too much. Acids drive CO2 out of the carbonate and bicarbonate buffer system. A lot of CO2 can be released in the short term. The CO2 evaporates…