You gotta put some kind of fish in there to get it to cycle. You will have to monitor your water. Watch it go from no ammonia to high ammonia, and back down to zero again. That the short version of cycling. Gotta get beneifical bateria built up and the time varies between tanks due to bioload, temp, size, etc. I have heard of it being done in a week, but probally more like a month, depending.