Sometimes nitrites get out of control, producing a phenomenon known as a nitrite spike . It is called «peak», because after nitrites are in a very high concentration, their presence drops again. Nitrites are toxic to fish, becoming fatal in concentrations exceeding 1 milligram per liter. Measures for its control and adjustment are usually taken when the concentration reaches 0.5 mg / l.
Why does a nitrite spike occur?
To understand how a nitrite peak can occur, you have to know the nitrogen cycle , basic to understanding life inside the aquarium. Inside the aquarium, which is a closed biotope, waste is produced that comes from all living elements: plants and fish. Plants provide debris, such as their leaves, and fish contribute feces and food debris. All these remains decompose, generating ammonia and ammonia. Ammonia is not a dangerous substance for fish, but with a water pH greater than 7, ammonia appears, which is a toxic product.
NO2 in the aquarium
In a healthy aquarium with the presence of nitrifying bacteria, ammonia and ammonia are converted to nitrite NO2. But it is still a relatively toxic product, we need (thanks to bacteria) the nitrite to oxidize and become nitrate, a compound that is used by plants as a nutrient. For the bacteria to break down nitrites into nitrates, they need a more or less long period of time, which can vary depending on whether the bacteria in charge of the process are present or not in the necessary measure. If the bacteria present in the aquarium cannot break down the nitrites into nitrates, nitrite spikes occur.
Most common causes of a nitrite spike
I think it has become clear that a nitrite spike is caused by a lack of beneficial bacteria … but why are those bacteria not present? There are three common causes, why bacteria may be absent:
Still it has not completed the cycling of the aquarium , or has not performed well.
After a treatment . Many drugs to treat fish diseases have the side effect of killing beneficial bacteria
After a filter change or if we carry out an excessive cleaning of the filter
Everything you need to maintain your aquarium
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Measure nitrites in the aquarium
The only way we have to measure nitrites in the aquarium is by using an aquarium test . We have the typical strip aquarium tests, which will measure all levels: hardness, nitrites, nitrates, ammonia, ph … and we also have the option of using a test for nitrites NO2 . Nitrite tests should be performed frequently, especially when the aquarium cycling process is being carried out, but also when we suspect that something is not working well in the aquarium. We can suspect that there is an excess of nitrites in the aquarium if the fish remain on the surface for a long time or if they breathe with difficulty and move their gills very quickly.
Lower nitrites in the aquarium
Once we have detected an excessive concentration of nitrites, we have to proceed to regulate the levels to a concentration that is not dangerous.
You have to know that the «logical» way is for nitrifying bacteria to do their job, but if they are not present in sufficient numbers or simply not present, we have to take drastic measures before the problem is tragic for our fish.
We have two ways: add live bacteria, which would be the most logical but slowest procedure, or use a product that is capable of reducing nitrites. My recommendation is to use Prime Seachen, Sera Toxivec or Nitrit-Minus, two products that will quickly reduce nitrite concentrations by converting them to organic amines, which will be eliminated by bacteria.
Nitrates in aquarium water
The by-product of nitrites is nitrates. You may find that they recommend water changes to reduce nitrites, but this is not true. What reduces water changes is the presence of nitrates. To maintain an adequate level of nitrates, we must establish some aquarium cleaning routines ( siphoning ), along with periodic water changes. It is interesting to keep a detailed diary in which we mark the water changes made and the levels of nitrites and nitrates, to determine an optimal calendar for our aquarium, depending on the inhabitants: plants and fish.