What to trust...Coralife or Ranco Thermometer

[charleskeller]

I use several of the Coralife digital thermometers in my systems and have always trusted them. I got a used chiller with a Ranco temperature controller a while back and it read 2 degrees higher than the Coralife. Since I was getting consistent readings from multiple Coralife units I considered them more accurate and adjusted the Ranco accordingly.

Right now I have a Coralife and the Ranco probe side by side in the return of my sump and the Coralife is 78.3 and the Ranco is at 82. There is another Coralife probe in the overflow box and it reads 78.1. It seems the Ranco is now about 4 degrees higher.

Does anyone else have these problems? Could the Ranco be calibrated? What is the most accurate way I can determine my tanks temperature?

[zigzag]

same problem here, +4 degree difference between a coralife and a neptune aquacontroller temp probe :-/

[BrassMonkey]

my coralife is 2 deg off.

[nozleman]

Same problem here, same exact as zigzag, Lets hear from the temp, guys?

[AcroporAddict]

Coralife digital thermometers suck. They are wrong. Trust your Ranco. They are industrial controllers.

For just basic temperature indication, you are better off with a suction cup glass type.

[DSMpunk]

Dont blindly trust either one. There is an easy way to test the accuracy.

Fill up a glass with ice water (as much ice as possible,crushed ice works best) stick the probe in the ice and see if it settles to 32 degrees.

Adjust your reading accordingly.

[charleskeller]

Great idea for testing DSMpunk!

I filled a decent sized glass full with crushed ice and then with water. I placed three methods of measuring in and waited about 2 minutes for them to all stabilize and watched them for another 5 minutes.

Here's my readings...

Coralife Digital Thermometer - 28.6
Ranco Digital Controller Thermometer - 33
Glass Tube Thermometer - 30.5
Zoo Med Laboratories - TO BE TESTED LATER

Since water freezes at 32deg and the Coralife probe and glass tube were not in an ice cube its safe to say their readings are inaccurate by at least 3.4 and 1.5 degrees respectively, putting the Ranco with a reading of 33 as the obvious winner here.

I recently purchased the Zoo Med Laboratories thermometer and noticed when I started using it the reading was 3-4 off from the Coralife. It is with my 1.25g pico tank that I loaned out to a teacher for her classroom. I'll test it when I get it back later today.

I should have posted this long ago...looks like I've been off by a couple degrees for a while.

Anyone have a digital thermometer with an alarm they could test also? I am interested in getting one and would like to see how accurate they are.

[THE ROOK]

Those coralife digitals are junk. I had two & within a month both were off by 10 degrees or more. I would trust the Ranco much more as they are commercial / industrial pieces.

I use a mechanical meat thermometer to verify that my AC Jr is ok.