Stick-on Vs Digital Thermometers

[serbusfish]

My Juwel Rio 125 and my parents Rio 300 both have stick on thermometers, mine was reading at 25'c and my parents 26'c. Today I purchased 2 digital thermometers, and they are coming up at 22'c in my tank and 23'c in my parents tank. Is is normal for stick on glass thermometers to be so inaccurate?

[KingFisher]

Yes, unfortunately the stick on thermometers are notoriously inaccurate.

[Goes to 11!]

Yes, unfortunately the stick on thermometers are notoriously inaccurate.

+1 What he said.

I use the alcohol ones myself.

[serbusfish]

The greatest thing about this is it turns out ive been running my tank without a heater for the past month or so!

As you most likely are aware Juwel heaters have an orange light when they turn on, and you can hear them click on and off. Well a while ago after doing a water change when I plugged my heater back in I noticed the light didnt come on. I at first suspected it had broken but noticed my temps were staying at 24/25'c as I wanted so thought nothing of it. Now it turns out my tank is simply being kept warm by the temperature of my bedroom

Time for a new heater

[genocidex]

i like the alcohol ones but i also like the digital if you can get a good one. but i always have a back up thermometer in every of my tanks so i can check for inaccuracies. stick on ones only measure the glass temp. the idea is the glass should be the same temp as the water but thats not always true

[jeffs99dime]

Alcohol or digital like the others said.

[Goes to 11!]

the idea is the glass should be the same temp as the water but thats not always true

Or ever.

The glass, Any glass.. Will not be the same temp as the water or the air or the milk or coffee in it.

Go stick your hand on the window and see for yourself if it's the same temp as the room, Glass is an insulator.

[Shidohari]

+1 to all of the above. all three of my tanks have digital thermometers on them because i got tired of using the flashlight to read the number on the sticky one that came with my ten gallon tank set. I never even bothered using the one that came with the second ten gallon tank set i got.

[dbosman]

Please don't stress over accuracy of a inexpensive device that isn't ever going to be accurate and doesn't need to be. Even testing labs using laboratory grade thermometers have to have them re-calibrated periodically.

Thermometers are great for indicating temperature trends.

The specific temperature of a tank isn't particularly important at any given point in time. The range of temperature over time, for most fish, can matter, but generally not as much as some feel it is. Some specific fish are less tolerant of change, just as some of any living organism are.

For some species, close enough to comfortable for the keeper, is fine. Natural bodies of water change temperature over the course of a day, over the course of a river or stream, or moving a few inches from a sunny exposure area to an area in the shade.

Next time you're near a rack of thermometers, check them all for consistency.

[serbusfish]

I now have a heater in my tank and its slightly unnerving that the stick on glass thermometer is reading 28/29'c but my digital is only at 25.5'c...