Aquarium Thermometers

You will need a thermometer to verify that your tank stays at its proper temperature. Two types are commonly available. The traditional bulb thermometer works the same way as the ones you can buy for your house. They either hang from the top edge of your tank, or float along the surface. The second common design is a flat model that sticks to the outside of the glass. In this design, liquid crystals activate at a specific temperature, either highlighting the numerical temperature or a bar that slides along a scale.
Aquarium thermometers can be rather unreliable so, thermometers are good for verifying that your temperature is not too far off, but may be off by several degrees in some cases. When buying a thermometer, look at all the thermometers and pick one that has an ``average´´ temperature, rather than one of the extremes.