Accurate Thermometer

[Tritone]

I’ve noticed that the temperatures listed on my Aquael heater differs a lot from the digital thermometer.

This got me thinking and reminded me that Temperature is one of our most important parameter.

So I started reading dozens of reviews in search of the most accurate Thermometer. 
As usual, best choice is on the other side of the Atlantic in North America whilst we, poor old Continent citizens are mostly at the mercy of cheap made in China products that seem to be popular on Amazon but receive mediocre reviews on specialised sites.

So, let’s hear it from the horse’s mouth; what are the most accurate Thermometers for Aquarists?

 

Thank you.

 

 

[M. Tournesol]

Thermometer are cheap sensor to make. What do you mean by accuracy? 

6 minutes ago, Tritone said:

cheap made in China products that seem to be popular on Amazon but receive mediocre reviews on specialised sites.

And what do you mean by "specialised sites reviews"? 

 

[Tritone]

Just now, M. Tournesol said:

Thermometer are cheap sensor to make. What do you mean by accuracy? 

And what do you mean by "specialised sites reviews"? 

 

For Accurate I mean that a reading of 27c should mean the water IS 27c, not 25 or 29. 
For Specialised sites reviews I mean forums and sites run by aquarists. Such as this one.

 

 

[M. Tournesol]

The problem is not accuracy in this case, It's the in factory thresholding of the prob. 
You should just buy a glass thermometer or a kitchen electronic thermometer and adjust your Aquael heater without looking at its listed temperatures.
It's what I did with my inline heater. 

[M. Tournesol]

What I did not understand is if you were asking where to find a heater with an "accurate listed temperatures" or an accurate heater controller?

[Tritone]

1 minute ago, M. Tournesol said:

The problem is not accuracy in this case, It's the in factory thresholding of the prob. 
You should just buy a glass thermometer or a kitchen electronic thermometer and just adjust your Aquael heater without looking at its listed temperatures.
It's what I did with my inline heater. 

Thank you. The problem is not all of them have probs. Factory thresholding is not what the general consumer concerns he/herself with. They just want a product to do what it says on the box. 
But I accept your suggestion with thanks.

[M. Tournesol]

If you want to sleep soundly, you should buy a heater controller. Most of them even give you the possibility to set two different heaters. If one heater broke, the second will take the relay 😉

[Murphs_Reef]

That's why I like the Eheim heaters, you need to calibrate them to the correct temp. Then set the temp. If all else fails get a controller link Inkbird and your a bit better off 👍🏼

[Tritone]

6 minutes ago, Murphych said:

That's why I like the Eheim heaters, you need to calibrate them to the correct temp. Then set the temp. If all else fails get a controller link Inkbird and your a bit better off 👍🏼

How do you calibrate them? Sorry, I’ve no idea.

 

** IGNORE**

 

I don’t really want to buy another heater. 
 

 

[DaJMasta]

Temperature is not one of the most important parameters in terms of accuracy, really, the important thing is that it is not constantly changing much in the short term.  Real reefs will fluctuate several degrees over the course of the year and can fluctuate significantly over the course of a day or two for localized events, and thanks to livestock being collected from different places and depths, you could easily have some deepwater species where 26C is warm for them and some shallower tropical species that 28C is warm but in the realm of normal yearly temperatures for them, so even if you're a couple of degrees off, it may be the ideal temperature in your tank.

 

The bigger issue would be fluctuation over the course of hours of a degree or more, and most heater thermostats can manage better than that.  If you're trying to tightly control temperatures for seasonal spawning concerns or whatnot, then having a thermometer that is pretty accurate and has good long term stability is important, but really not in a ton of other situations.  Actually calibrated thermometers exist, which will specify an accuracy, maybe a linearity, and a calibration period that they need to be rechecked at the end of to verify they are still accurate, but they are expensive and I haven't heard of people relying on them for managing tank temperature.

[Tritone]

11 minutes ago, DaJMasta said:

Temperature is not one of the most important parameters in terms of accuracy, really, the important thing is that it is not constantly changing much in the short term.  Real reefs will fluctuate several degrees over the course of the year and can fluctuate significantly over the course of a day or two for localized events, and thanks to livestock being collected from different places and depths, you could easily have some deepwater species where 26C is warm for them and some shallower tropical species that 28C is warm but in the realm of yearly temperatures for them, so even if you're a couple of degrees off, it may be the ideal temperature in your tank.

 

The bigger issue would be fluctuation over the course of hours of a degree or more, and most heater thermostats can manage better than that.  If you're trying to tightly control temperatures for seasonal spawning concerns or whatnot, then having a thermometer that is pretty accurate and has good long term stability is important, but really not in a ton of other situations.  Actually calibrated thermometers exist, which will specify an accuracy, maybe a linearity, and a calibration period that they need to be rechecked at the end of to verify they are still accurate, but they are expensive and I haven't heard of people relying on them for managing tank temperature.

We had a heatwave here a few weeks back and I nearly lost my sanity trying to keep water temperature below 30c…. Or so the thermometer indicated. Now we’re in cooler weather and while my heater indicates a temperature of 25c the thermometer goes closer to 28 and I’m having to fan it with a Dyson still thinking it’s too high. 
I know that in the ocean currents and temperatures range and surge but the fish can swim away to where is more comfortable. 
In my tank they have to put up with what I manage for them.

Maybe I’m overreacting but I’ve managed to keep things steady so far and would like to continue doing so if at all possible. X

[M. Tournesol]

 

7 minutes ago, Tritone said:

Maybe I’m overreacting but I’ve managed to keep things steady so far and would like to continue doing so if at all possible. X

No, you're not.

What you should look at is if your thermometer is just offset or if it's inaccurate. Being offset is not a problem but being inaccurate ...

[PeterU]

22 minutes ago, Tritone said:

my heater indicates a temperature of 25c the thermometer goes closer to 28

How do you know which one is closer to being accurate?

[Tritone]

Just now, PeterU said:

How do you know which one is closer to being accurate?

I don’t. 
But I’ve noticed that during heatwave the heater indicated Higher Temp than setting like it should giving me a bit more confidence than the therm which gives me a reading of past 27 with a powerful fan blowing onto the tank.

So rather than guess I would like a Thermometer that is at least credited by most people to be reliable.

 

 

[M. Tournesol]

8 minutes ago, PeterU said:

How do you know which one is closer to being accurate?

by buying three different cheap glass thermometers?

Edited August 21, 2021 by M. Tournesol

[M. Tournesol]

3 minutes ago, Tritone said:

I would like a Thermometer that is at least credited by most people to be reliable.

My ADA NA THERMOMETER thermometer is reliable at +/- 0.5 °c

[Tritone]

1 minute ago, M. Tournesol said:

by buying three different cheap glass thermometers?

I just need to buy one if someone has done a bit of testing and can tell me: This Thermometer by X brand and x model is accurate! 
I didn’t think my original question was going to be so challenging, LOL

 

Just now, M. Tournesol said:

My ADA NA THERMOMETER thermometer is reliable at +/- 0.5 °c

Finally!
 

Thank you.

[M. Tournesol]

https://modestfish.com/best-aquarium-thermometer/ ??

[DaJMasta]

32 minutes ago, Tritone said:

Maybe I’m overreacting but I’ve managed to keep things steady so far and would like to continue doing so if at all possible. X

That's just it, stability/consistency/precision does count, accuracy doesn't so much.  Accuracy is the absolute temperature value being correct, the other three are the temperature not changing too rapidly or drifting to something way off, and it's that consistency and stability that are the important part.   That's why chasing a number is less the issue than just making sure it reads that way consistently.

I'd say as a rule of thumb, a dedicated thermometer will likely be more accurate than an integrated thermostat number (like the Eheim Jager series use), but the base accuracy for an inexpensive digital thermometer is going to be at least +-1C plus a percent, at best really, where more likely it could be +-2C from the indicated temperature since the cheap ones aren't going to be tested or adjusted in a meaningful way, and any non-digital thermometer is probably in this ballpark accuracy as well.  Better thermometers would be ones rated for use in the foodservice industry, since they will have a minimum accuracy specification to meet for measuring temperature of food to pass health inspections.

The way people try to make less than accurate thermometers better is to try several and average the value to assume that as a likely better midpoint - the idea is that the accuracy response of many thermometers is probably approximately gaussian, so testing hundreds of thermometers on the same reference would yield a distribution results around the true temperature, but especially with inexpensively manufactured consumer gear, we can't be 100% sure of that either, though averaging them will likely at least reduce the impact of outlier readings.  Long story short, this method yields better results more of the time, but the error bars for the testing are basically the same.

Now the consistency of measurement over time and the consistency of one thermometer measuring against itself is going to generally be a lot better than either of these accuracy specifications, so if your thermometer is in the right range for temperature (even if not ideal), and is reading consistently, you are probably doing a good job with your temperature regulation, and this is the important part.

[Tritone]

I’ll go with the following: I have a food grade thermometer that I swear by for my cooking. I don’t know why I haven’t thought about it before. I just need to change the battery. Then I shall see wether or not the cheap one in the tank is measuring porkies.