Filter Cartridge Change

[Dumbo the Fish]

So I have a 2 gallon betta tank with a filter cartridge that has been there for over 6 months. It’s falling apart and hasn’t been doing it’s job. I’ve swished it around in tank water many times but it’s still not working. I have a whisper for 1-3 gallons. The cartridge is hard so I can’t break it in half. How would I still preserve the BB while changing the cartridge?

 

[coralbandit]

See if you can squeeze the new one in with old for a week or so ?
If you have gravel and decorations in the tank bacteria are living on those surfaces also..
Just don't clean the gravel or glass the week you change cartridge...
Feeding a little less will help the filter not be overloaded also for the first week..