Whats more accurate
 

So i have a pinpoint temp probe and a mercury floating thermometer.There is a difference in about 4 degrees.I don't know but i'm thinlikng the pinpoint is off and going to throw it out if thats the case.What are people's feelings about this?

How old is the pinpoint? Also for the love of god if its actually a Mercury thermometer get it out of the tank!

Pretty sure its an OH one though, if so and its not damaged it should be bang on.

Pin point is brandnew.Floating thermometer is new also.I'm assuming its mercury.

You need a third fourth thermometer to ID the suspect.

+1, no doubt both of these will give you alternate numbers as well though :lol:.

Which color is the fluid in the thermo? If its red its fine.

Get a NIST traceable thermometer. Temperature is really important in a reef tank. When you spend thousands of dollars on livestock, there is no point to cheap-out on a thermometer.

What is a nsit thermometer?Actually i didn't think the pinpoint wasn't cheap

NIST=National Institute of Standards and Technology.
These are professional grade thermometers that have been properly calibrated.