1. Aquarium Heaters
If you decide to have a Cool Water Aquarium, you won't need an Aquarium Heater or a Thermometer. Click here read more about Cool Water Aquariums.

But if you choose to have a Warm Water Aquarium, you'll need both an Aquarium Heater and a Thermometer. Click here to read more about Warm Water Aquariums.

Heaters come in different sizes that are measured in watts. Multiply the number of gallons in your aquarium by 5 to determine the size heater to get for your aquarium.

For example, a ten gallon aquarium needs a 10 x 5 = 50 watt heater. Similarly a 20-gallon aquarium needs a 100 watt heater. Click here for help on calculating the size of your aquarium.

Carefully read the directions that come in the box with your aquarium heater where you'll read about how to adjust the heater, so your aquarium water is in the correct temperature range. Click here for more information about adjusting your heater to the correct temperature range.

Don't remove a hot aquarium heater from an aquarium. It may overheat and crack, or crack when it goes back into the water. Unplug the heater 15 minutes before removing it from the aquarium and be sure to plug it back in, after it's back in the aquarium.

The directions that come with an aquarium heater usually recommend putting the thermometer far away from the heater. For example, put the heater in the back-left corner of the aquarium, and put the thermometer in the front-right corner.

Buy the stainless steel type of thermometer shown below. If not damaged, this type will last many years.

Thermometers that attach to the inside of the aquarium often come loose and float around inside the aquarium, where they are difficult to find and to read quickly.

Thermometers that stick on the outside of the aquarium glass will soon fade, become difficult to read, and so are not recommended.

Aquarium Thermometers usually have a green range printed on them that indicates the recommended temperature range for warm water fish.