The biggest reason fish die in new tanks — and how to avoid it.
Fish waste produces ammonia, which is toxic. Beneficial bacteria in your filter turn ammonia into nitrite, and then into much safer nitrate.
How to cycle
- Use a bacteria starter and a small ammonia source.
- Test water every few days.
- When ammonia and nitrite read 0 and nitrate appears, the tank is ready.
Never clean your filter media under tap water — rinse it in old tank water so the bacteria survive.