You can use that, if it has proper readings and doesn't tell you when to stop cooking the chincken, haha.
Or you can be 100 % safe and get one from your petstore for 3 $
Anyway good luck!
glass will work fine - my tank thermometer is a glass one that has a sucker that sticks to the side - works better than the magnetic strip i had (supposedly they are good - but i think other wise)
the magnetic ones takes temp reading of the cold glass too - so its not very accurate..
just make sure your thermometer is submerged the whole way in the water.