How is the ammonia broken down?
Initially, the ammonia level will rocket, as there are few bacteria present to break it down. After a few days, autotrophic bacteria called Nitrosomonas start to grow. These nitrifying bacteria break down the nitrogen in the ammonia by oxidising it to nitrite. Nitrite is less harmful, but would still be very dangerous to any fish present. The ammonia level will normally remain very high for a couple of weeks in tropical aquaria, although it could persist for much longer if the water is cold, salty or contains chemicals that affect the bacteria.
