Heating/temperature issue - bad heaters or temperature readers?

[davidinga]

I have a 210 gal with two eheim heaters a 300w and a 125w. The 300w is set at 78f and the 125f is set at 76f. The 125w comes on all the time while the 300w is generally only on occasionally. For temperature readings all I currently have is a plain Jane mercury glass tube and a coralvue digital probe. The glass tube reads about 78f and the digital says 80.6f; how far off so these digital things get or do you think the mercury tube is the one wrong?

Is my 125w heater messing up or is the dial at the top of these not very accurate?
Should I invest in some better temperature reading item? Like what?

Oh, and I stuck both temperature testers in the DT to make sure being so close to the heaters weren't throwing them off.

alt="" />

alt="" />

alt="" />

Sent by Samsung Galaxy Note 2 and Tapatalk 2

 

[heathlindner25]

I don't think the digital one is quite as accurate as the old school one.

 

[davidinga]

So I turned the 125w heater down to 75f and it still turns on while 300w stays off and the temperature readings show 80.4 digital and 78f mercury glass tube.


Sent by Samsung Galaxy Note 2 and Tapatalk 2

 

[jbadd99]

I ditched the stock heater controls in favor of a Ranco controller. I have never seen my tank stay at a more constant temperature according to every thermometer I have.

 

[jennm]

I'd trust the glass thermometer over the digital one. Learned that the hard way.

 

[hiimsean]

I'd invest in a controller.

 

[atmercure]

before i had a conroller, i used a ranco. it works great. gonna post it for sale if interested.

 

[skriz]

Your digital one is garbage. Don't trust it at all.

 

[johniii]

Put them both in a solution of 50% ice 50% water. Mix well. The good one will read 32 degrees f.

Sent from my DROID RAZR using Tapatalk 2

 

[sewer urchin]

put them both in a solution of 50% ice 50% water. Mix well. The good one will read 32 degrees f.

+1

 

[davidinga]

JohnIII;857596 wrote: Put them both in a solution of 50% ice 50% water. Mix well. The good one will read 32 degrees f.

Sent from my DROID RAZR using Tapatalk 2

Thanks I'll do that!

My money's on the analog mercury one being good and the digital being off...

Sent by Samsung Galaxy Note 2 and Tapatalk 2

 

[chris s]

Coralvue advertises the digital to be accurate +/- 1.5F. :huh: Not exactly accurate in my opinion.