The nitrogen compounds nitrite (NO2) and nitrate (NO3)

The decomposition of organic nitrogen compounds consisting of excrement, dead parts of plants, food-rests etc is divided into several stages.

1. Ammonia and ammonium develop
     from organic waste. The water plants absorb
     ammonium as a nitrogen fertilizer.
     Ammonia is highly toxic.
    
     The transformation of ammonia and
     ammonium is dependent on the pH-value.
     Ammonium develops with a low pH,
     ammonia with a high pH. In view of this,
     there is no possibility of »ammonia poisoning«
     in aquariums with low pH-value.

2. Nitrite which is toxic for fish, develops
     from ammonium/ammonia.

3. Nitrite is converted into nitrate which
     is only toxic in high concentrations and is
     absorbed by water plants as a nutrient.

These decomposition stages are carried out by micro-organisms, which form a complex unity of life with other micro-organisms in the filter and base of the aquarium. Increased nitrite or nitrate indicates that the biological balance in the aquarium or pond has been disturbed. In this case part of the water should be replaced and the reason for the disturbance identified. To create and maintain an effective culture of micro-organisms we recommend using aquavital nitrigon1 and aquavital nitrigon 2 for filter bacteria.

Nitrite, even in low concentrations is toxic for ornamental fish. If the nitrite-square on the multistick changes colour, adjustments need to be carried out immedately. Part of the water needs to be changed and aquavital nitrigon1 and aquavital nitrigon 2 added for filter bacteria.