Old filter cartridge?

[gialdino171]

Ok, so I have the Marineland Penguin 100 filter that has a mini-bio wheel. I just changed the filter cartridge yesterday. I have the old cartridge in a stocking hanging in the tank on the side. I wasn't sure if the biowheel had enough bacteria to compensate for the filter change, and was worried that a mini-cycle would occur without the old cartridge. Just wondering how long I should leave it in there, thanks.

 

[Cichlid Kid]

Most of the HOB filters that have bio wheels on them don't offer enough surface area thru the bio wheel itself. I mean its a nice concept and all dont get me wrong. Its just not enough so if u changed the inside cartridge then i would say yes you will have a mini cycle.
Hanging the old one in a sock doesn't offer much help unless its directly in the water current.

 

[siva]

What would be more effective is take the fiber material off the old cart and shove it in pressed against the new cart. Another thing you can do is add a nylon bag with additional filter media if there is any open space inside the filter. Then you can change out the cart and bag at different times.