Accidentally Left Heater On Dry


While doing a water change I forgot to turn my heater off. This resulted in the top half of the heater being exposed to air while running. Luckily I saw it in time and turned the heater off before it was fully emerged. It didn't explode, smell burnt, or make any strange sounds, but maybe it's because it was only set 3-4 degrees above room temp. I'm wondering if it suffered internal damage or something and I just can't see it. Can/should I just turn it back on and continue using it? Has anyone had experience with this type of situation? I'm going to test it on a fishless tank of water tomorrow, and see how it goes.
I am keeping it off for now, because I'm about to go to bed and do not want to wake up to fried fish.
All responses would be greatly appreciated!

P.S. Also, if it is broken, I probably can't get one until a few days later. It's around 70 degrees in the house. I've forgotten to turn on the heater overnight and it dropped down to 67/68 ish, so I know my platies and cherry barbs will be ok short term. but how will they fare for a few days? It's a 55 gallon so it's slowly losing temperature.


Looking at my heater the top 3" is the controls not sure what heater you have but if its similar than no harm done. I did notice if the top of mine isn't under water it says error instead of the temp and shuts off.


The heaters are just electric resistance elements, other than the glass breaking the only thing I could possibly think of breaking would be the thermostat in it and I don’t really see why it would (other than the fact that they just fail anyway). I’d look real close to check for small signs of cracking on the glass to be safe. What heater is it? Is it actually one of the glass ones or is it one of the plastic ones like the Aqueon Pro. I believe many of them now have overheating auto shutoff.

I would stick it in a bucket, make sure it gets the water up to temp and shuts off, add some cool water see if it kicks back on and shuts off again.

Another suggestion for the future, I have my filter and heaters on the same switch with my heater at or below the suction of the filter...if I drain back my tank so the filter is sucking air it would remind me to turn off the switch if I hadn’t already. It also prevents the tank from evaporating below the heater line without it going unnoticed.

  • Thread Starter


Thanks for the advice! I know this is a pretty old thread, but just in case anyone was wondering how it played out, the heater works normally now.

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