[manda]

I am in the process of cycling a 10 gallon to hold three male bettas in a divided tank.

i have always used sponge filters because they dont make much current. these sponge filters i use also have carbon. they are made by pen plax. its just a little filter you hook into your aeration and it suction cups to the side.

my question is... you are supposed to change these every two to three weeks. how can i keep a tank cycled if i have to change the filter media? Can i leave a dirty cartledge in the tank. maybe just place it in the middle of the tank on the bottom. and put in my two new cartridges?