Recommendation for digital thermometer?

I'd like to purchase a couple of digital thermometers for my two tanks that have at probe that I can leave in the water permanently. Anyone have any recommendations and/or links? Accuracy is very important.

Thanks!

I use this one.

http://www.drsfoster...fm?pcatid=12089

I use this one.

http://www.drsfoster...fm?pcatid=12089

How accurate is it? Furthermore + or - 1.5 F. seems like a lot.

+/- 1.5 degrees shouldn't be a worry because you can get that kind of fluctuation in different parts of the tank.

+/- 1.5 degrees shouldn't be a worry because you can get that kind of fluctuation in different parts of the tank.

Makes sense. I wasn't being unappreciative just in case it seemed that way. I saw some comments about the above product on Amazon.com and some said it wasn't very accurate as in having two of them in the same tank and they gave different readings.

" two of them in the same tank and they gave different readings"
Most consumer and hobby stuff comes from China so not surprised at readings but on the other hand, if accuracy is a must then simply put both probes into a glass of cold water (check low end) and warm water (aquarium normal) and record the differences against a standard mercury thermometer in the same vessel. Then record the adjustment factors needed for each digital. This is common in any lab and required weekly for most so why not for our hobby if accuracy is needed? Then you don't have to worry about if it is different environmental temperatures or they really are both calibrated differently.

Usil

Edited by Usil, 26 November 2011 - 11:38 PM.

" two of them in the same tank and they gave different readings"
Most consumer and hobby stuff comes from China so not surprised at readings but on the other hand, if accuracy is a must then simply put both probes into a glass of cold water (check low end) and warm water (aquarium normal) and record the differences against a standard mercury thermometer in the same vessel. Then record the adjustment factors needed for each digital. This is common in any lab and required weekly for most so why not for our hobby if accuracy is needed? Then you don't have to worry about if it is different environmental temperatures or they really are both calibrated differently.

Usil

As a somewhat additional check, try this: Prepare a container of ice (mostly) and water and check your thermometer. The ice/water should give you very close to 32F/)C. Then check the upper end with boiling water to get 212F/100C. Note that if you have altitude issues, this will change. You can Google temperature/altitude to see where you should read.

As a somewhat additional check, try this: Prepare a container of ice (mostly) and water and check your thermometer. The ice/water should give you very close to 32F/)C. Then check the upper end with boiling water to get 212F/100C. Note that if you have altitude issues, this will change. You can Google temperature/altitude to see where you should read.

I did not go with the ice and boiling methodology as the use of the tank thermometer would never see these extremes. It would be ok for a reduced temperature spread around the tank temperature as the slope would provide the needed adjustment factors around the temperatures that it would be used for.

Usil