Courses
Underground Aquarium · Free course
The Nitrogen Cycle
Why new tanks kill fish, and how to make sure yours never does
~35 min 8 lessons Certificate + profile badge
Learn how the nitrogen cycle works, how to cycle a new tank with or without fish, how to read your test results, and how to keep a cycled tank from crashing. Seven short lessons, a quiz after each, and a final exam.
Free · No prior experience needed
What you'll learn
- 1What the nitrogen cycle is
- 2New tank syndrome
- 3Fishless cycling, step by step
- 4Fish-in cycling
- 5Reading your test results
- 6Bottled bacteria and seeded media
- 7Mini-cycles and how to recover
- 8Final exam
Earn your certificate
Finish every lesson and pass the quizzes to earn a shareable certificate and a “Certified Cycler” badge on your profile.