How long will a cycle last

[C.w.deegan]

I have a tank that was fully cycled but the fish I had in it got moved into a bigger tank. The filter and heater have been running but other than a few assasin snails there's no other fish in it. It's been empty about 5 days I want to restock it with a school of guppies but I'm not sure if my cycle crashed due to lack of bio load its a 20 gallon with a hob cartridge filter on it

 

[Aiken Drum]

If the tank is running then you shouldn't see any significant loss of beneficial bacteria for a few weeks.

 

[C.w.deegan]

Ok thank you