When I was using it, I was able to leave it on for 3-5 hours no problem. However, I was using it in bursts. For a constant use, you will need a steady bubble supply. I do want to warn you though, this will produce A LOT of bubbles. I can't image using this in a mall. I was using it for rave-style parties and it did the job quite well. It will also leave a very slippery mess on the floor, especially if using it all day long. This might be a liability you might want to avoid. Or look into a machine that produces much less bubbles.