Temperature Control

[Xdpker]

Hello everybody, first post here. I am having trouble keeping the temperature constant in my tank. I have it set to 73 degrees on my 25 watt heater in a 5 gallon tank. However the temperature in the water is 82 degrees right now. It is 11:30 am and the outside temperature is 73 degrees. When I turn on the overhead lamps, the temperature jumps up even more. Any suggestions?

 

[Noahs ark6]

Is your heater stuck on on?. If your heater has a little light study for a while to see if it goes off