there it is then - the light is happily going on and off (it comes on when the temperature drops to 27.8 then takes the tank back up to 30.1) and Manwell has explored his tank and found his "happy spot" at the back near the light but not directly under it. I'm not 100% satisfied with the tank (I would like a mister to maintain humidity) BUT it's a far cry from where we started.