I think mine was two weeks, then again I put chemicals when I first started (duhh?!?!!). It should've taken less, but yeah it's about two weeks. I first started with 3 lbs of lr, and some ls. Not long afer that I put my sebae clown in there. The next day, damsel, crazy? Yeah I was. I ended up giving the damsel back to the lfs. Don't like him. But the clown is still alive till now. I had a penguin biowheel filter going on when I first started, and it's still there now. That's about it. Oh yeah I added the BIOZYME, works for me.