right now twice a day, this past weekend it was three or four. I am working now so it has to wait until late afternoon. This past weekend I would shock it at least twice a day trying to reach shock levels. My tests never seemed to show much of a raise in chlorine level an hour or even two after shocking. It is like the chlorine level would not change. Of course I heard "locked up" from Leslie's but that makes no sense to me. If I dump enough chlorine (which I thought I did) there should be a change.