Filter media, comes in many forms. Filter floss is merely the final stage.
Dependant of the type of filter you have. The bottom is usually a course sponge or ceramic soporax type media, then the next layer is your absorbant type media, such as nitra zorb or ammo aorb or ammo-carb or just a less course media. Then the third stage is the filter floss. This last layer usually is placed on the very top so that it traps the smallest particles of dirt and "polishes" the water before returning it back to the tank. Different fishkeepers will tell you that the do things differently and so they may because it's what works for them. As a new starter to the hobby, you won't go too far wrong with the method that I've suggested. Then as your skills develop you can change it to how it suits your pocket and your fish.
