Does hydrogen peroxide help against algae?
From time to time, the use of hydrogen peroxide (H2O2) is recommended to combat algae. The chlorophyll of the algae should be oxidized. Because plants have thicker cell walls than algae, plants are not harmed.
preliminary conclusion: The use of H2O2 is not recommended > Fish can be permanently injured or killed.
However, H2O2 can definitely be harmful to the fish. Due to its aggressive oxidation, the skin of the fish and their gill epithelium are literally burned. Damage to the gill epithelium causes cells to deposit on top of the epithelium, which actually consists of just one layer of cells. This deposit and the additional change in the flow conditions in the gills make it difficult for the fish to breathe. These changes offer bacteria and parasites the best possible settlements. Even if the use of H2O2 initially appears to be successful and without damage, fish can die from the long-term effects.
Different reports of experience are probably based on the fact that the effect of H2O2 depends greatly on the used concentration depends. A locally different concentration in the aquarium also plays a role, which in some places in the aquarium can be significantly higher and therefore more dangerous than after complete mixing with the aquarium water.
H2O2 must never be poured directly into the water, but only slowly dripped into the aquarium after dilution with aquarium water. The water must be aerated before and during the application of H2O2. An existing CO2 supply must be throttled to a minimum. When using H2O2, the aquarium must be monitored closely, as fish can be damaged very quickly. The breathing of the fish in particular must be monitored. Since the gills can be affected without this being noticed immediately, the breathing of the fish must also be observed after the treatment. The manufacturers of medicines that work on the basis of H2O2 point out that their products may only be used with certain water conditions (no soft water, etc.).
The use of H2O2 can cause the aquarium water to become cloudy. The turbidity can be caused by bacteria that feed on organic substances floating in the water (algae, microorganisms, bacteria, fish gills, etc. destroyed by H2O2) and lead to a bacterial bloom through massive multiplication. Turbidity can also be caused directly by organic substances. These are invisibly dissolved in the water and are changed or fragmented by the oxidation so that they fall out as a fine ‘mist’.
Per arguments
- H2O2 works very well against algae.
Contra-arguments
- Plants stop growing and may even die.
- Fish can be severely damaged or even die.
- The causes of the algae development are not eliminated.
- After the end of the H2O2 treatment, the algae will appear again.
- Algae even grow on oxidizers that work with H2O2.
- Hair is bleached with H2O2.
- Reports speak of massive fish deaths after the use of H2O2.