How to know when cycling is completed

[DuncanNAbednago]

Cycling with pure ammonia and towards the end of the cycle, just wanted to confirm: when 2ppm ammonia is reduced to 0 ammonia and 0 nitrites in 24 hours, tank is cycled?
Thanks!

 

[Azedenkae]

Yes. Though 1ppm works too (almost all aquariums, even heavily stocked ones, only produce <1ppm ammonia a day max). Only like REALLY heavily stocked, heavily fed tanks produce 2ppm ammonia a day.

So yeah, if not already, just wait until both ammonia and nitrite drop to zero, before re-dosing ammonia - 1ppm or 2ppm, your choice.

 

[kallililly1973]

Should also show trace amounts of nitrates. How long has it been cycling? Usually takes anywhere from 4-8 weeks.

 

[ProudPapa]

Cycling with pure ammonia and towards the end of the cycle, just wanted to confirm: when 2ppm ammonia is reduced to 0 ammonia and 0 nitrites in 24 hours, tank is cycled?
Thanks!

That's how I understand it. Of course you should be seeing a significant amount of nitrates as a result of those two being consumed, so it's generally recommended to do a water change before adding fish.