Best thermometer

hi all, just wondered which is the best and most reliable themometer, i have two standard glass ones and a digital one, but the readings are about two degrees out, the glass ones at either end of the tank are exactly the same reading but the digi one is reading two degrees higher, both heaters are set the same but even they are set higher than what any of the themometers read, i know sometimes you set heaters slightly higher because of poistion and circulation etc, but wondered which themometer was more acurate, thanks again guys, see ya soon....

Its probably the glass thermometers are correct. The digital thermometer requires calibration & if not perfectly calibrated (most cheaper ones aren't) the temperature will be a bit off as the digital thermometer isn't directly reading/outputing like the glass ones do. Same goes for the heaters but it is also a factor of ciculation/orientation/etc as you noted.

yup glass is best. Tetra used to have a great one, where one can read the temp properly without using a magnifying glass, but I cant find these anymore. cheers jk :thumbup:

thanks guys for reply, digi one was a cheapy, get what ya pay for i expect, will stick to glass in future, thanks again

Just mark on the digital one in nikko -2 so you know to subtract that from the regular reading. Or on the outside of the glass somewhere if the whole digital goes in the water. It wipes off with a bit of wet filter wool when you don't want it any more.

Hi, my 6 digital thermometers give 6 vastly different readings!
Do you recommend any particular brand of glass thermometers or just the cheap ones with a suction cap?
Thanks a lot

i would not go for the cheapest and also not for the most expensive. I use tetra ones but do not know if these are available in Australia. Also remember, it also depends on the size of the tank and heaters you have. If you have 2 thermometers in one large tank they can give different readings due size of tank and water movement. cheers jk :thumbup:

the problem I have with thermos is the suction caps dont seem to last long.

Interesting to see this thread as i am just going through a little experiment of my own atm. As already stated here, the digital ones are not the most accurate. I had them on all my tanks except one which has a glass thermometer. I also have a digital thermometer with an external probe that we use in pathology labs when i used to work there so i assume it is relatively accurate. I recently used it to check the temp in each tank and the results were not good, inaccuracies of between 2-4 degrees celcius. When you're trying to achieve specific temperature drops with water changes this is not good enough and to make matters worse the degree of inaccuracy varies depending on what the water temp is, ie. at 30C it may only be 1.5 degrees out but at 26C it can be over 2.5 degrees out so it makes it a little hard to try and just allow for the inaccuracy when you don't know how inaccurate it is at a specific temp.
So, i have started buying various glass thermometers and seeing which ones give the most accurate readings. Once i find the best one i will then use them in all my tanks. The first one i have tried is about 1 degree out at 30C. The original glass one i have is only .5-.7 degrees out which is good enough for me.
I am going to try a couple more and see how i go. At a couple of bucks each i figure it's worth it just for the peace of mind.

It is definitely a problem & I'm sure we would all be breeding more with more accurate temperature readings. Some tanks physically feel hotter than others that according to the thermometers are meant to be cooler.
I spent about $30-40 on my last thermometer that is now dead after 6 months & new batteries wouldn't even fix it. Very frustrating
Please keep us updated how you go beencees

I use good old fashioned glass thermometers when the suckers loose grip you can get a bit of extra use out of them by soaking the sucker in boiling water it makes them supple again, I also like the hang on glass thermo they don't drop off are really slim and look tidy

agree with everyone else, digitals suck, I use a $4 glass one with magnets, no suction cups. Magnet on thermometer inside tank,and a round plastic covered magnet to sick on the outside. Only prob is when cleaning the glass , sometimes I knock it and thermometer falls to bottom of tank, but easily just take the outside magnet and catch the thermometer and run it up the glass back to position. Got them at aq store. hth

That sounds like what I need. Hopefully I can find them in Australia.
If they are $4 there they will be $20 here haha

I also tried the digital ones ended up with two for each of my 2 tanks and they all gave different readings !
Gave up with them
I have a mercury one from where I used to work but am a bit wary of using it in case i break it
I mainly use the digital one on my tds meter its 2 degrees out according to the mercury one so compensate by setting heating two degrees higher

The problem I have is that the tank temps change with the weather but the digital thermometers don't always adjust accordingly so I really had no idea what temps my tanks were

.....and the results are in.

Although hardly an exhaustive test i tried out a number of conventional (ie. non-digital) thermometers from ebay. I checked accuracy at a variety of temperatures and they ranged from 1 degree celcius out to 2.6 degrees out.
Of course it was the last one that i recieved that proved to be the most accurate, out by only 0.2 degrees which i am more than happy with :thumbup:
Hopefully it wasn't just a case of being lucky and getting one good one out of a batch so i have ordered a couple more of these which, all being well, will be what i shall use in all my tanks.
Here's the link for anyone who may be interested.
Dirt cheap as well

http://www.ebay.com.au/itm/Aquarium-Glass-Thermometer-Temperature-Aquarium-Fish-Tank-Submersible-Suction-/271032837213?pt=AU_Pet_Supplies&hash=item3f1ad0e45d

i was told the Sera thermometers are best
i also find the digital one i have is out compared to the suction cap style ones
stick on thermometers are a waste of time on my tank, as it has 10mm sides

Stick on thermometers don't last more than a few months and are jolly hard to scrape off the glass too.

My thermometer temperatures are all over the place again and I want to get it sorted
It's unbelievable how useless the 6 different types I have tried are.
You would think it would be easy these days to find an accurate thermometer!

Has anyone used TDS & temp testers in one? I have a TDS tester that seems accurate but how can you tell? I was thinking of buying an accurate one from a scientific instrument company or similar. Has anyone tried that?
Thanks

I just ordered one of these. FINALLY I will know the real temperatures of my tanks and hopefully assist my fish in breeding. A good investment.
I will advise my temps too once I test it

Link is below for anyone interested. An easy transaction with free express post

http://www.instrumentchoice.com.au/instrument-choice/environment-meters/temperature-meters/probe-thermometers/hi98509-checktemp-1c-pocket-thermometer