[Fenderman]

I’ve always used the kind that attach to the side of the tank with a suction cup. I can never get them to remain attached for any length of time, no matter how well I clean the glass and suction cup. I’m looking for a better idea.

 

[blackghost]

Just keep buying them till you get one with a good sucker. Or buy some suckers and try them.
Or, surface tension will keep it stuck to the glass if the flow in the tank isn’t too strong (you may have to turn it to read it).

 

[sharkweek0178]

I use a couple of cheapo digital thermometers, one on each side of the tank. I like having more than one so if one isn't working, I'll know.

 

[Fenderman]

I did some poking around on Amazon and found a thermometer that attaches to the glass by means of a magnet on the outside of the tank. Seems like a better idea than the suction cup. I think I’ll be ordering one of those.

 

[yee.simon]

Those Side hanging type of thermometer would be good. or just forget about the suction type and let it float

 

[funkyperfesser]

I use the kind that sticks to the glass and it's decent enough. My heater is fixed temp anyway

 

[Fenderman]

I received my thermometer today. I like it. Very easy to use, and you can locate it anywhere you want by just moving the external magnet around. Problem solved!

 

[Lord PJ85]

I use a digital thermometer, you can set it to °C or °F, it sits on the outside of the tank with a thin wire hanging into the water, just wrap it around your pipping. Had it years and its literally maybe a few degrees more from what my external heaters state. They are very good and accurate.