THE NITROGEN CYCLE

The nitrogen cycle in the aquarium describes the process by which harmful ammonia (and subsequently nitrite) in your tank are converted by cultivated, naturally occurring bacterial colonies into the less harmful end product of the cycle, nitrate, which may then be controlled through water changes.

 

The nitrogen cycle occurs in nature, as do the two types of bacteria involved in it, and they are completely harmless - beneficial, actually.

 

However, in order for them to balance your aquarium, the bacteria must exist in colonies large enough to process the ammonia from the fish (and the resultant nitrites from the nitrification process) at the same rate that they are being produced.

 

For more information regarding ammonia, nitrite and nitrate, visit our WATER CHEMISTRY page.

 

      AMMONIA (NH3/NH4) NITRITE (NO2) NITRATE (NO3)
PRODUCED BY:
  • Excreted by fish in the aquarium as a waste product
  • Produced by decaying organic compounds in the aquarium (ie: fish waste, uneaten food, dead fish, dead leaves from live plants)
  • Excreted by Nitrosomonas bacteria - the first type of bacteria involved in the nitrogen cycle
  • Excreted by Nitrobacter bacteria - the second (and last) type of bacteria involved in the nitrogen cycle
CONSUMED BY:
  • Nitrosomonas bacteria - the first type of bacteria involved in the nitrogen cycle
  • Live aquarium plants
  • Nitrobacter bacteria - the second (and last) type of bacteria involved in the nitrogen cycle
  • Live aquarium plants
  • Live aquarium plants
DANGEROUS LEVEL IN THE AQUARIUM:
  • Any (must maintain 0 PPM)
  • Any (must maintain 0 PPM)
  • 20 PPM or more