Water temperature is at 82!!

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Aquarium Advice Activist
Dec 5, 2013
I went out and upgraded my heater to an Eheim heater and set the temperature to 78. When I came back home 4 hours later, the temperature was 82 and I think it's because of my t5ho bulbs. So, I set the temperature on the heater to 75 and it's still at 82 and then before I went to sleep, I turned off the lights and set the heater to 78 and when I woke up it was still 82..

What gives?
. I didn't know I had to calibrate the heater. My baaad
Last edited by a moderator:
I never heard of having to calibrate a heater before,that's a new one for me.I thought you just set the temp and it would be fine.
I find with my heaters that are rated for larger tanks I have to keep the dial setting lower, at 75 to keep it at 79*
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