Floyd R Turbo
Aquarium Advice Addict
A larger water change will not affect the bio colony. The ammonia goes down as the bio colony establishes in full. Until there is enough ammonia consuming bacteria to immediately convert it to Nitrite, you need to keep it under control with PWCs. Same with Nitrite portion of the cycle. With fish present producing waste, if there is excess ammonia you don't have enough of a bio colony established to consume it, so you might as well remove it, because the fish will make plenty more. As long as you don't vacuum the gravel or rinse off the bio media, you could theoretically do a 100% water change. The vast majority of bacteria aren't floating around in the water, they're adhered to the surfaces.How come "what"?
The ammonia goes down as the bacteria feeds on ammonia increase to the point that the ammonia is being consumed as fast as it is being made leaving nitrites.
Then the nitrites increase until that type of bacteria starts to comsume it, leaving finally the nitrates which are removed by PWC's.