Quote Originally Posted by serbusfish
I now have a heater in my tank and its slightly unnerving that the stick on glass thermometer is reading 28/29'c but my digital is only at 25.5'c...
Take the digital thermometer out of the tank. Dry it off and let it register room temperature for a couple of hours. What is that reading?

Also, where are the thermometers? Placement can change the reading. Swishing your hand through your aquarium. Do you feel changes from stratification?