Confused about temperature in my tank

[this is me]

I've been using a glass thermometer for quite awhile but just the other day while cleaning the tank, i drop the glass thermometer on the floor and broke it. So yesterday i got myself the pinipoint wireless thermometer. When i was using the glass thermometer, it showed that the tank temperature is 80. My Wonbros, heater is set at 79 and usually turn on and off at this point. My pinpoint shows something different, the temp is 83!!:eek1: and the heater is still working(set at 79)!! I got paranoid so i turn down(75) the heater. The tank temperature is now 81 and the heater is on. I'm so confused.
You dont have to calibrate a thermomemeter or anything right? My heater probe is just cleaned the other day.

 

[Lourdes]

I didn't calibrate mine.. Pinpoint is pretty acurate... good luck

 

[davidrupe]

My little digital thermometer thingy, don't remember the brand. Got it at AA for $20. It reads the room temperature when I set it to air, different than my house thermostat. I don't know which one is right... So either my room temp is way off or my tank temp is off, I don't know.

 

[this is me]

My little digital thermometer thingy, don't remember the brand. Got it at AA for $20. It reads the room temperature when I set it to air, different than my house thermostat. I don't know which one is right... So either my room temp is way off or my tank temp is off, I don't know.

hahahhah, so that makes the two of us.

 

[~Flighty~]

If it has a wide enough range, pute it in RO/DI with lots of ice and see if it reads 32

 

[davidrupe]

Oh, and my little glass thermometer reads what the digital one reads so I have a feeling my house one is not right. The fish are happy so I am too.