Two liters of bio-substrate would probably fill all the baskets you want to fill in two filters. I bought two two liter jars when I was ordering. I have three canister filters that came with some media, and I have about a half liter left over after adding. As long as you are paying shipping, might as well stock up. Its nice to have extra around. Then when I put fish in a QT
, I take some media from the canister for the QT
filter, then add fresh stuff.
You can still jump start your new tank. Take part of whatever you have in your established canister now, and put it in the new filter. That can cut weeks off the fishless cycle. your charcoal bag will work, cuz it gets colonized. Just don't take all the media out of your established filter. Yes sponges work too. Everything gets colonized, including gravel. You could even put gravel fromthe established tank in the new filter to speed it up.
edit: oh, fluval sells the ceramic coarse mechanical ceramic stuff, two or three boxes for two filters? I am not sure that you need this, but since it came with my fluvals, I just bought a box or two to add to it. After 3 months, there wasn't much in the coarse ceramic noodles. Either it doesn't work, or my tank doesn't have much coarse stuff to trap. When I open my goldie tanks canister I will see how much coarse stuff it traps.It still provides surface area for bacteria.