Bad heater?

[DiverGirl82]

The brand new 50w finnex heater I have in my QT says it's 79°. However, 2 digital thermometers say it's 77°. Who do I believe? I had the heater set to 78° but saw the thermometer said 77.1 so I bumped it up to 79°.

 

[TheEngineer]

They are probably all correct. The issue is the error bounds for each. My Finnex is +/- 1 degrees. That means if the real temp is 79, it could read anywhere from 78 to 80.

The only real way to know is with a calibrated thermometer.

 

[twilliard]

How far away is the probe from the element? Also is the probe in direct current?
It took me a lot of trial and error to get my probe placed in the proper position as to not pick up the element heat.

 

[DiverGirl82]

It's only a 10g tank so they're pretty close. Maybe 5-6 inches. I've got the heater in the middle and the thermometer on the side.

 

[miyags]

That happens to me alot. Which ones right??? I just had a heater stop working temp was down to 69 before I caught it. The little light on the heater was still on. It's better to error on the cold side, than to cook everything.

 

[NanaReefer]

I've always kept a floating glass thermometer in my tank for reference. Can't beat their accuracy.

 

[jd371]

I've always kept a floating glass thermometer in my tank for reference. Can't beat their accuracy.

Same here, although it's not the floating type but one that is attached with a magnet to the side of the tank. There is no difference in temp readings between the two.

 

[DiverGirl82]

Now the brand new 200w finnex heater in my dt is doing the same thing. I bumped it up to 79° and the digital thermometer says it's only 77.5°.