Heater malfunction!


So the other morning I couldn't see my betta anywhere in the tank. He usually comes out after the lights come on in the morning and greets me to get fed. I was running late to work so didn't have time to really search. When I came home I found him behind the filter dead and the water was really hot. I have a cheap 10 gallon heater from Walmart, I think it was 10-20 dollars and it can be completely underwater. Well it was still trying to heat the water, which had to be hotter than 86F degrees because the thermometer wasn't even reading. Was wondering if anyone has ever had this problem? And also wanted to warn anyone who has one of these heaters



Oh you poor thing, and your betta too What kind of heater was it? You can call the company and explain what happened, they may refund you the heater and damages. What size tank is it? Wattage shouldn't be more than twice as much as needed, unless your tank is absolutely massive, in which case you need more than one heater. Sorry about your baby! And don't feel bad, it wasn't your fault


I've heard of heaters malfunctioning, usually when they fail they just shut down but it sounds like this one failed open. I've gotten to where I'm constantly checking the temp's on my tank's because of all the horror stories. I finally added digital thermometers and lit them up so every time I walked by the tank the temperature stared me in the face. I will never buy another glass heater...they're too unpredictable but I have also heard of titanium heaters failing as well. I guess the only way to be safe is to be checking the temp all the time but most of us rarely do that. So sorry for your loss...that sucks!


If the heater used a simple bimetal strip and mechanical contacts (as many of the inexpensive ones do), then a common failure mode is that the contacts "weld" closed, and that makes them stick. So then the heater won't shut off even if the temperature gets very hot.

If the unit uses a solid state device to electronically switch the power, then the most common failure mode for thyristors is to fail shorted (again, a closed circuit, that keeps power on to the heater) so again, the tank will overheat.

When a friend and I decided we wanted better aquarium heaters than what we could buy, back in the early 1980s, we got thermistors, a particular cheap IC that's made for heater control, and high voltage, heavy duty triacs, and modified a bunch of standard, cheap, glass heaters.

The way we wired them, the electronic control operated as you'd expect. But as a failsafe, we kept the cheap bimetal strip original thermostats, but set them to open about five degrees above our "real" setpoint.

They work great, and are pretty safe because both systems would have to fail before you'd overheat a tank to the point of killing anything.

Later, what I've done is to build separate heater controllers that use a temperature sensor mounted independently from the heater(s) plugged into the controller. And again, I just set the mechanical thermostats in the heaters to a temperature a few degrees above what the main controller wants to see.

That way, if the main controller fails shorted (as they are won't to do), at least the heaters' thermostats will keep things from getting out of hand.

I know it'd cost a buck or two more, but it seems like someone should be selling heaters with a failsafe backup thermostat commercially.

I'm so sorry for what happened. That's heartbreaking.

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