Cheese Specialist
Newbie
You should run the old filter sponge and new together (jam them in if needs be) or cut it in half and do that so you change half at a time. Saying that I never change mine, too much like hassle. All you are doing is taking out the good bacteria, it doesn't need changed until it is literally falling apart.
As for the cycling, gravel will help a lot.
Consider cutting the media up or just squishing it in, it will still run ok. Are you using amonia to cycle? If you have put old gravel in now but no fish/amonia source in the good bacteria will die very quickly.
~ Dana ~
As for the cycling, gravel will help a lot.
~ Dana ~