LOL, seriously slow your insecurity. And by the way your still wrong. First off what does temperature change in a room have anything to do with wether heat tape creates ambient temperature?? Your arguing a point with an irrelevant side topic. Temperature change in a room is what a thermostat is for. He asked what size heat tape to use. I replied the 11" so it would create more ambient temperature without the floor getting as hot as say 6" heat tape to create the same amount of ambient temperature. You replied that heat tape does not create any ambient temperature change which is ridiculous. Guess what most homemade incubators use to raise ambient temps?? Heat tape. Guess what most rack manufacturers use to heat their tubs and create ambient temps, yup its heat tape. Guess what I've put under all the different cages that I've ever had from homemade to vision and so on to create floor heat and raise ambient temps...heat tape. Was I a bit rash when it comes to my reply, sure. heat tape raises ambient temps in my tubs 11 degrees over room temp with keeping floor temps at 91. In my incubator it raises the ambient temps 17 degrees over room temp with ease. For anyone who is still unsure about this google: "flexwatt create ambient temps" or call up any rack manufacturer and ask them if the heat tape will raise air temp in the tub. Get the 11" tape.