Keeping Old Bacteria In A Tank, With A New Sponge Filter?

[woodstock]

I'm making a sponge filter pretty soon as soon as I get the materials. What I'm really concerned about it the bacteria in the bio-cartridge (this filter has something just for the bacteria). Since I simply won't be using the filter anymore (don't really bother asking, I'm set on the sponge filter), I may have to just keep the bio-cartridge inside the actual tank. How long will I have to keep it in there?

And I may have to keep it in a plastic box sealed off with mesh or something, but it seems like it could ruin a tail VERY, VERY, VERY easily. So I may just go with the minimum time, since it will take up a lot of space

 

[Tolak]

Run both filters at the same time for about a month, then remove the filter with the cartridge. As an alternative you could tie the cartridge to the sponge filter for a month.

 

[woodstock]

So a month = safest amount of time for a colony to establish? What would be the absolute minimum, just out of curiousity.

 

[Tolak]

I wouldn't consider anything less than two weeks. I constantly keep spares running, just in case.

 

[woodstock]

Alright, thanks very much : )