@wangling I can tell you what I do....I fill the pot with distilled water (to max level). I do not use the rack that comes with the pot. When the water boils, I drop in the neb parts (after they have been soaked and rinsed) and turn the pot to low. Here's the most important point: I set a TIMER for 10 minutes. It's so easy to forget the bubbling cauldron so there's a risk of it running dry. I do not believe there is an automatic turn off. I either use my phone or an actual portable timer. Good luck. Hope this helps!