best thermometer?

[gale]

I bought this floating thermometer and it says the little betta tank is 84 degrees. i'm pretty sure that can't be right since the light is tiny and the house is only 70 degrees. So I"m assuming it is wrong and am going to replace it. Is there a type or brand that is best? I have the stick on the outside kind on my big tank and never even questioned it. The fish seem to be doing ok in there.

 

[Lateral Line]

Mercury thermometers are the most accurate of the non-electronic types. You should get +/- 0.1C accuracy from even a cheap one.

Alchohol types are less accurate, but still good enough for most purposes. I would expect one to be within 1C.

The stick on ones give "an indication" of the temperature - they neither are, nor claim to be really accurate. They are often +/- 2C or more.

The thing to do is have at least one good thermometer. Read each tank and note, mentally if you are so inclined, the difference between your good thermometer and the tank thermometer. Then you'll know that "tank 6" says 27, but you know it allways reads a couple of degrees high.

There are a lot of electronic thermometers around. A lot of them are in fact, not terribly accurate, if it is cheap, then it probably isn't going to be a star performer. A reasonable electronic unit should be accurate to +/- 0.1C.

When choosing thermometers, look at a number of them in the same situation, try to average the temperatures they give, ignore any examples that read high or low.

Remember however, a person with a thermometer always knows what the temperature is, a person with 2 is never quite sure...

 

[gale]

Thanks. I went today and totally forgot to get a thermometer. The lfs guy was vacuuming (again and it was nearly 2 hours before closing time) and acted like he could hardly wait for me to get out of there (along with another customer) so he could start up again. I did manage to get my gravel, plants and bloodworms at least. I forgot to check if they had fluorite. Shoot.