Beneficial bacteria

[Jen]

Hi I’m new to the hobby and have question. I just recently upgraded my 20 gal tank to a 40 and successfully moved my fish and everything is great on that tank. I want to now use my 20gal for a new fish. I know I can instant cycle using existing media but my question is How long does it take for beneficial bacteria to grow on new media placed in my established tank. Back story: I was using a Cartridge filter on my hang on back filter but got smarter and added filter sponge and filter rings which I want to move to my new tank to cycle it. I just don’t know how long the media needs to be in an established tank to be able to move to a new tank to instant cycle. Any advice would be great. again I’m new to this hobby about 6months so I’m still learning 🙂 thanks 

[StephenP2003]

I've had success in putting fresh media in an established tank for two weeks before moving it to a new tank. I've heard two weeks minimum, so that's what I went with.