I have a cycled tank and am thinking about starting a second tank. What is the best way to do this? I have heard to use a sponge for this maybe? Do I buy a sponge and soak it in the tank for awhile and then place it in the new tank?
No, I doubt that will have any effect. You can run a sponge filter in your current tank for about a month to get a nice bacterial colony growing on it. You could also take some gravel from the established tank and put it in the new tank. If you use scrubbies or bio balls or ceramic rings as your bio media, you could take a handful and dump them into your new tank.
Just remember to add ammonia every day, otherwise the bacteria will die. Keep doing it until ammonia readings are 0, nitrite readings are 0, and nitrate readings are >0. By seeding, you could cut down on the cycling time by a lot, depending on how much bacteria you've introduced.
No, nothing scented. Get some pantyhose, and buy a few big shrimp at the supermarket, put them in the pantyhose, and dangle that in your tank. The decaying shrimp will release ammonia, and once the tank is cycled you can pull the pantyhose out (and that way the shrimp doesn't leave a bunch of particulate matter in your tank).
And not in the tank. In the filter right before your mech stage brazier to clean out. Algea wafers work great, but any food will do. That's how I keep my qt tank functioning when uninhabited