I have a Top Fin Filter and I use the replacement cartridges: http://www.petsmart.com/product/index.j ... Id=2752295
but how does Bio filter cartridges work? Can i just put them in or do I have to wait a few days or something before i can put my turtle back in.
Then again, my Top Fin cartridges are chem/bio/mech. What's the difference between the regular cartridges and the BIO 3?


