I did a test run with 4 gallons of water in the 6 inch deep pan. I used a thermometer in the pan with the 4 gallons, with a lid on. The temp controller on the unit is numbered. On number 1, it took about one hour to increase the water temp 10 degrees, and when I turned the unit off, the temp gradually increased another 3 degrees. Later I did a run on number 2. It took about 30 mins to increase 10 degrees, and again when I turned it off there was a 3 degree creep. Then I tried to see how hot it would get on maximum temp. It topped out at about 160 degrees. So with that in mind, I may try keeping a close eye and turning the heat down as I get within about 5 degrees of target.