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Thermometer

4K views 21 replies 10 participants last post by  Tyyrlym 
#1 ·
What thermometers have you guys had good experiences with? ANybody tested to see how accurate they are? I have two of the regular glass type that stick to the glass. They are about 10 degrees away from each other when they are in the same tank. I'm looking to upgrade to something much more reliable.
 
#3 ·
i bought a whole lot of thermometers all at once and tested them in one tank and they were all within a degree of one another......I have seven tanks right now and wanted to make sure all were giving me the same reading.........As far as a quality thermo i dont really have an answer for that.......I bought whatever was cheap and they all work fine for me.......i prefer the floating type over the suction cup type
 
#5 ·
The stick on generally not accurate. If you want an accurate temperature measurement then your instrument needs to be immersed in the liquid. For me the simple glass ones that you stick on with a suction cup work very well. Don't bother with the Coralife digital ones, they're inaccurate and hyper-sensitive.
 
#6 ·
I also use the glass ones you can either float or suction cup to the inside. I used to have some Corallife digitals and I found them to be off by about 4-5 degrees F.

I wonder why your glass ones are so far off in the same tank. Did you place them in the same area of the tank to compare or were they at opposite ends? It may be that you heat is not being evenly distributed throughout the tank.
 
#7 ·
I did not know the stick on ones were unreliable. Ive never had any problems.

For thermometers, I was always told to put it as far from the heater as possible. My old suction cup one broke in my tank once and from then on I haven't used any in-tank thermometers. Anyway, anyone have a brand they can recommend? From the posts here, I'm beginning to think i need to get an in-tank thermometer again.
 
#8 ·
I too would be interested in brands. I know walmart has them for less than $2, although i would rather get them somewhere else. Petsmart has them for less than $3 i think.

To better answer the questions. Yes, they were side by side in my tank. I was testing them before i put them in the other tank. For some reason they are roughly 10 degrees off. No idea why.
 
#10 ·
Mine are all Hagen. $2.99 from Fosters & Smith. Due to shipping I always bought them with a lot of other stuff.

The stick on ones are unreliable for the simple reason that they don't measure the actual water temperature. They measure the temperature of the outer surface of the tank material. Well, the people who make the stick ons don't know a lot of factors such as what material your tank is made of, glass or acrylic which have widely varying thermal conductivity. They don't know the thickness of the material of the tank, thicker materials will be cooler on the outer surface. They don't know the temperature of the room you're in, colder rooms make the outer surface cooler. All these factors can impact what that outer surface temperature really is and the manufacturer can't know what they are, so they make assumptions. Maybe they assume it's a glass tank, 1/4" thick, with a room temp of 74 degrees (an example, not the actual assumptions). If you have that kind of tank and room conditions the stick on works great, all their assumption are correct. However the more you deviate from those assumptions the less accurate the reading is.

The only way to reliably measure the temperature of a material is to take a reading from the material itself. I don't trust a thermometer that isn't immersed in the water or a digital that doesn't put it's probe right in the water.
 
#14 ·
I've never bothered with digital. I use the suction cup glass type myself. Of course, a stick-on thermometer is going to be a better choice for something like a big cichlid that could break a glass one or try to eat a digital probe. I learned this lesson after my brother-in-law's Texas cichlid pulled a really expensive digital instrument (temp, pH, TDS and maybe some other measures) into the tank by yanking really hard on the probe.
 
#16 ·
I had a digital and it sucked. My oscar was always chewing on the wire so maybe because it was always moving around but the temp would vary wildly. I assumed it was the heater going bad and then the batteries died so I dropped in a floating one that was supposed to have a suction cup but it just floated free and lo and behold, the temp was perfect and never fluctuated. The next time I ordered from fostersmith I bought three or four of the bargain suction cup ones. You just can't beat mercury.
 
#19 ·
I just bought a new 20 gal Aqueon deluxe kit (newbie here) and it says it comes with a "digital thermometer" and I got excited. Turns out that just means one of those stickers that goes on the outside.

After reading this thread, I think I should go buy a submersible one, but after iamntbatman's story, I don't know what I should do.

Which of these would be ideal?
Zoo Med digital thermometer (I like this style, I like the simple readout types. Are they reliable?)
Lifeguard little time or temp dig clock/thermometer (This one too)
Top Fin floating glass thermometer (This one seems simple, it can be suctioned inside)
 
#20 ·
if you stick with a floating type WITHOUT the suction cup it is alot harder for any large fish to break them.........They work the same, but with the suction cup keeps the thermo right next to your tank and allows fish to keep banging it against the side...........with a floating type the fish will just knock it around your tank and eventually lose interest.......
 
#21 ·
I have a suction-cup glass thermometer in my 15g and it works well. I recommend immersed-type thermometers, sicne they are generally more reliable. I agree with it being a bit hard with overly active and large fish. It isn't a problem in mine, though, since all I have in there are a betta and 2 small plecos.
 
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