The heater may be defective but more than likely your tank is just way too high. The lights and other devices may be keeping your temp. up. As I am sure you are aware heaters do not cool things down.
It is a good idea to have two heaters in a tank just to be sure that at least one Thermostat/heater is working properly. They do fail by just not working at all or sticking on all of the time. The tell/tale light is nice but a hand test daily tells you if the tank is too cold or getting too warm. Your hands are very sensitive to temp. variations.
On the subject of putting your hands in a tank...be careful! There are a lot of electrical devices in a tank and shorts are common. If your fish act hinky or you get a tingle, especially on a small cut, you have a short. Stray electricity is dangerous. Turn off all electrical devices before working in a tank. Repair all shorts quickly.
I have never had a heater go bad but the Hobby abounds with stories so it can happen. Your heater sounds OK but as with any device calibrate it with a Thermometer you trust and set it for where you want it to be. If you have two heaters set one a couple of degrees f less than what you set the main one for.
It is a good idea to have two heaters in a tank just to be sure that at least one Thermostat/heater is working properly. They do fail by just not working at all or sticking on all of the time. The tell/tale light is nice but a hand test daily tells you if the tank is too cold or getting too warm. Your hands are very sensitive to temp. variations.
On the subject of putting your hands in a tank...be careful! There are a lot of electrical devices in a tank and shorts are common. If your fish act hinky or you get a tingle, especially on a small cut, you have a short. Stray electricity is dangerous. Turn off all electrical devices before working in a tank. Repair all shorts quickly.
I have never had a heater go bad but the Hobby abounds with stories so it can happen. Your heater sounds OK but as with any device calibrate it with a Thermometer you trust and set it for where you want it to be. If you have two heaters set one a couple of degrees f less than what you set the main one for.
