So, yesterday was very hot.
I have a heater set to low in one tank, and no heater in the other, just a light.
Last night when I came upstairs, I looked at the thermometers...and the tank with the light was NINETY-TWO DEGREES!!! I couldn't believe it! I turned off the light, of course, and this morning the weather cooled off and the temperature was down around 78...but wow! What a scare! I'm just glad that the betta was alright!