ok now..all setup how much of a difference should there be between having the temp prob in the tank on the inside or directly to the heat cable? because there's a huge flucuaton between the thermostat turnign on and off and have it to almsost all the way low and thermometer says it gets up to 96-97 then drops all the way to 88deg...WTF...i'm confused...dont' want the themometer probe in the tank for fear fo having to tape it..a little more help please.