In order for it to cycle your tank, the bacteria on the filter need a food source... like some fish waste.
How long has it been in your tank, and do you have fish? The answers to these questions will help us answer your original one.
In the meantime, go up to the top of the freshwater beginner forum and read the stickies regarding getting started. They're very educational, and will help you get down to whatever questions you really need to ask us... things you don't get after reading up on cycling your tank. Also, you won't have to wait for an answer to a question if you find the info there.
Sounds like you're on the right track, and may have read up on cycling before now. If so, just provide us the details and we can answer your question a bit more intelligently.