Sep 17, 2011 #1 M murad Aquarium Advice Apprentice Joined May 8, 2011 Messages 25 i know about nitrogen cycle but how does bacteria enter
Sep 17, 2011 #2 B blert Aquarium Advice Addict Joined Sep 4, 2011 Messages 2,706 Location Florida It's in the air, on surfaces. It's all around you. It's free!
Sep 17, 2011 #3 senemedar Aquarium Advice Freak Joined Sep 6, 2011 Messages 363 Location UK ...or you add them with a solutions like Tap-Safe or similar. They're definitly not free then