Excessively high nitrite values are caused, among other things, by:
- insufficient performance of the filter
- overstocking
- overfeeding
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High nitrite values almost always occur in a newly set up aquarium. Therefore, the running-in period must be observed before fish are placed in the aquarium. The peak of a nitrite increase is with the so-called nitrite peak achieved, ie that there is an inequality of bacteria in the aquarium. There are two types of bacteria that maintain the biological balance in the aquarium: Nitrosomonas and Nitrobacter. The latter are responsible for breaking down nitrite and multiply much more slowly than the Nitrosomonas. Since, for this reason, there are more bacteria in the start-up phase of each aquarium that convert ammonium or ammonia into nitrite, but too few that then process the nitrite into nitrate, the nitrite value rises, the nitrite peak.
If the nitrite value is above 0.5 mg/l, an immediate water change is the method of choice.
The nitrite value should always be at least below 0.3 mg/l when the first fish are introduced. It is better if the nitrite value is below the detection limit. If the water test used only shows nitrite values higher than 0.3 mg/l, the nitrite value should definitely be below the detection limit. The value is below the detection limit when no nitrite is displayed. You can assume that there will still be some nitrite in the water because the tests aren’t that accurate.
Since nitrite is very toxic for fish, if the nitrite level is too high, to avoid fish dying, the nitrite level must be reduced by several water changes so that the nitrite level remains below 0.3 mg/l. The cause of the excessively high nitrite values must then be found and eliminated.
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Lower nitrate levels that are too high
In well-established aquariums, nitrite is released from the filter bacteria converted to nitrate. Nitrate is used as a nutrient by the aquarium plants.
Possible causes of excessively high nitrate levels are:
- Nitrate levels are already high in tap water
- overstocking
- infrequent water changes
- overfeeding
The nitrate value should not rise above 20 mg/l, with drinking water up to 50 mg/l being permissible. If the nitrate levels in the aquarium water are too high, the nitrate level in the tap water should be measured first. If the value is already too high there, the nitrate content can be reduced with the help of an osmosis system.
Excess nitrate in the aquarium is removed with water changes. If the nitrate levels in the aquarium are constantly too high, you can leave the roots of philodendrons or ivy in the aquarium. These plants consume a lot of nitrate, which they then extract from the aquarium water.
If the nitrite or nitrate values remain too high despite all measures, it should be checked whether the water tests used are still correct. To do this, z. B. check a water sample at an aquarium retailer.
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