What is my aquarium temperature?

[HawkeyeDJ]

So I have 4 thermometers and no two of them read the same. Any suggestions on how one might determine the actual temperature of my tank?

 

[PeterC99]

Take the average.

 

[Idech]

Make them read the room temperature and the one closest to what it is is the one to keep. It will take several hours before they are ready to read.

 

[Adrift]

I would say take the average. Even with calibrated meters this can be off. If you have 4 thermometers in a room and your hvac system turns in the pattern of airflow can dramatically change the value by almost 2 degrees or more. The same is true with placement in fish tank. Warm and cold pockets will happen. Don’t scratch you head over what is said. The best practice is to take average. Another example after vip interior install on a 737 we take almost 20 measurements in the room. Then you guessed it take the average.

 

[snorklr]

if the digital ones go high enough try them in boiling water and see if they read 212...then again maybe they are accurate there and not lower...there must be lab grade thermometers available somewhere...this bothers me too as i'm setting my salinity with a hydrometer at 77 degrees and 2 digitals and my chiller display all disagree

 

[HawkeyeDJ]

if the digital ones go high enough try them in boiling water and see if they read 212...then again maybe they are accurate there and not lower...there must be lab grade thermometers available somewhere...this bothers me too as i'm setting my salinity with a hydrometer at 77 degrees and 2 digitals and my chiller display all disagree

I tried something somewhat safer. I wasn't keen on putting a plastic probe into boiling water. However, I did place two of the digital probes into a glass filled with ice and water. The results were interesting.

When in the aquarium, literally side-by-side, they were 3 degrees off of one another. 77 vs 80.

When they were placed in the ice water, they registered within a half degree of the other. 33.1 vs 33.6.