Nitrite (part 2)

In Nitrite Part 1 You may have read that a nitrite level above 0.2 milligrams per liter is harmful to your fish. And excessive nitrite concentrations can suffocate your fish. If you measure elevated nitrite levels, it's important to take measures, depending on the severity, to quickly lower the level and also to identify and eliminate the cause.

Possible causes of reed peak

A nitrite peak can occur due to:

We've started a new pond, and the biological filter doesn't yet contain enough nitrifying bacteria to break down the nitrite that's formed. Nitrite-degrading bacteria can only start to multiply after ammonia-degrading bacteria have done their work (a nitrite peak often follows an ammonia peak).
Our biological filter is too small (insufficient attachment surface for nitrifying bacteria) to process the full supply of nitrite.
We fed too enthusiastically in the spring, while the filter had not yet fully developed.
You've significantly expanded your fish stock. Your bacterial colony needs time to grow along with the increased food supply.
Toxic medication was used which killed the bacteria in the filter.
The filter material in the filter has been replaced, which means everything needs to be restarted.
The water and/or air pump has failed, causing the bacteria to not receive a food supply or resulting in a lack of oxygen.
Insufficient water was changed, causing the KH to be depleted. This caused a pH crash, killing the bacteria.
The filter has dried out, causing the bacteria to die.

So a lot can go wrong, be alert!

What to do in case of a nitrite peak?

Besides solving the cause, the first step is, of course, a substantial water change and good aeration. However, if the nitrite peak exceeds 0.4 milligrams per liter, I would recommend adding 1 to 1.5 kilos. salty per cubic meter of pond water. This may seem like a lot, but it's relatively small. For comparison, seawater, for example, contains over thirty kilograms of salt per cubic meter. So don't be afraid or hesitant. With 20 cubic meters in the pond and a nitrite level above 0.4 mg/l, that means 20-30 kilograms of salt in that pond!

This salt doesn't lower nitrite levels, but it does prevent the fish from suffocating due to oxygen deficiency. In part 1 of this article, I explained that nitrite binds to red blood cells, hindering oxygen transport to the organs. Salt dissolves in water to form a sodium ion (Na+) and a chloride ion (Cl-), with the chloride ion being the most important. Both chloride ions and nitrite ions are absorbed from the passing water through the gills and enter the fish's bloodstream. Chloride ions can also bind to red blood cells. Because there are more chloride ions (Cl-) in the water, fewer nitrite ions (NO2-) are bound (competition). Unlike nitrite ions, chloride ions do not hinder oxygen uptake. For example, if we ensure that there are ten times more chloride ions in the water than nitrite ions, we reduce the problem by a factor of ten. This gives you more time to get the filter up and running again. When the nitrite level actually starts to drop, you can lower the salt level again through your regular water changes. Until this happens, you'll need to add 1 to 1.5 kilos of salt for every cubic meter of water you change.