Water boils at 100 degrees Celsius so crank it up to the max, 108C, fill with hot water above the two lines at the Full mark (I now go to the top of the F), and set a timer for 3 hours (I plug into a timer that I set for 3 hours so it turns off automatically..."Outlet Timer, 7 Day Wall Plug in Light Timer Outlet, CANAGROW Indoor Digital Programmable Timers for Electrical Outlets, 3-Prong Dual Outlet for Appliances, 15A/1800W Brand: CANAGROW").Filling above the Full lines and setting for 3 hrs allows for the water carafe to fill up yet prevents the distiller from running dry and hopefully minimizes the coating of the inside & bottom with evaporated salts. I actually scrub the bottom and sides with a stainless steel wool to remove the salt coating every use to avoid the need to use the detergent (citric acid?) granules provided (about 4oz). Just takes me 5 minutes to do this. Also, note that this unit is unfortunately not waterproof, so be very careful when cleaning and filling in the kitchen sink to avoid water getting into the bottom electrical or control panel.I wish the glass carafe could sit a little closer to the distiller to better insure it will drip in the center of the glass carafe opening but the distiller is cone shaped so the glass carafe cannot get any closer. Just insure the distiller spout is pulled outwards and the glass carafe sits right next to the distiller. The unit comes with three little activated? carbon pouches of which one is placed in the outlet spout of the distiller [possible replacements: "12 Pack of Distiller Filters Made From Activated Charcoal. Works Great for Megahome and Many Other Countertop Distillers", Brand: iFilter]. The metal spout has to be firmly pulled down to clear the plastic, then slid outwards to put in or pull out the carbon bag. The bag does not fit the area very well, one just has to do the best to fit it in. Also, be warned that the top metal cover of the glass carafe can screw off, which might allow the glass to