Question on tank cycling

[Big Kid]

When you cycle a tank how long does it stay cycled for? Like if I leave it fish less and plant less and have nothing in it but the substrate and filter still running for a month after I have finished cycling will it still be cycled or do you have to keep adding something to keep it cycled?

[Faramir]

Think about it. With no ammonia source, what do you think will happen to the bacteria?

[online2]

I thought as long as they stay wet and got oxygen they be ok. Without food they just would not grow, they would go dormant till food source returned. But I could be wrong.

[carpguy]

The bacteria will die off without the ammonia source.

How was the tank cycled? Assuming the tank was fishlessly cycled, you can just keep dosing the ammonia until you're oterwise ready to go.

[JSchmidt]

I don't know of any source that suggests the bacteria that oxidize ammonia/nitrites have a dormant stage.

I think what you probably would see is that the bacteria could do OK without food for at least a week. After that you'd start seeing a gradual die-off of the biofilter that would probably leave you without many beneficial bacteria after a month or so.

I have aging tanks that have cycled that regularly go a week or more without any apparent loss of their ability process modest amounts (1 ppm) of ammonia. Even after two week vacations they seem capable of handling the ammonia, although I confess I haven't checked on whether any efficiency is lost over that period of time.

Jim