Filter Cycle question

[Scuba Guy]

How long will it take to bring a second 'new' filter up to bio-filtering capacity when using an established tank with an already fully cycled filter?

I am asking because I added a second identical bio-filter to my tank and before I take off the first one for a thorough cleaning, I want to make sure the new filter is up to speed.

Since the aquarium is not new and there is already a good filter, I assume it should take much less time for the second new filter to get a good bacteria population.....1/2 as much? 1/3 ? overnight?

Anyone have experience with this?

[Sasquatch]

Hard to say. I'd give a couple of week at least, a month at most.

It takes time for the bacteria to get established and sufficiently numerous to do a good job of biofiltration, but usually not as long as a full cycle since you don't have to wait for both the ammonia and the nitrites to spike.