Depends on the size of the tank. I have been using straigt ammonia and Bio-Spira in my 180 and it's been cycling for 16 days. it's still not done!! I'm still waiting for the Nitrites to drop, the ammonia did several days ago, right to zero. It takes time. Go to the piranha-fury.com website, there is a fishless cycle article pinned under water chemistry, check it out. Using fish to cycle is dumb. The ammonia and nitrites will stress them if not kill them, thus increasing risk of disease in the tank. Oh yeah, turnm the heat up to 84-85 degrees, that will help.