Heater Types

Unlike humans and warm-blooded animals, fish do not produce their own body heat. They must rely on the temperature of the water to maintain their body temperature.

Although some fish enjoy cool water, many aquarium fish are most comfortable in water that is above room temperature. Therefore, heaters are an important part of an aquarium environment.

Choosing a Heater
Choosing a heater is largely based on personal preference. Some owners prefer to go with the least expensive type, while others want nothing but the most high tech variety. Still others opt for the most unobtrusive type of heater, so the aquarium looks as natural as possible.

Before choosing a heater it's wise to learn the pros and cons of the various types of heaters. There are four basic types of aquarium heaters.

Immersible Heater - Often called hang-on, these heaters are the least expensive type. The heater control must remain above the water line, which is the biggest drawback. They can also be more difficult to set at the proper temp. However, the lower price makes this heater very appealing to anyone on a limited budget.

While I do not use this type routinely, if I see them on sale I'll purchase a couple to keep on hand for occasions when a heater fails in one of my tanks, and I need a backup heater.

Submersible Heater - These are more expensive than immersibles, but they can be fully submerged in the tank. Setting the temperature is easier, and they can be more readily concealed than the hang off the back type. The big negative is that you pay for what you get, so submersibles are much pricier than immersibles. They are also not easily repairable because the tube is sealed to allow the heater to be completely submerged.

Substrate Heater - Most popular in Europe and among plant enthusiasts, substrate heaters consist of heating cables installed below the substrate. They have the advantage of being aesthetically pleasing, due to the lack of hardware in the tank. They also heat the water more uniformly than immersible or submersible types.

Substrate heaters also promote plant growth, which makes them popular among those who keep aquariums with live plants. Unfortunately the downside is that the tank must be torn down to install or service them, and they are often not as readily available in local shops.

Filter Heater - This is the newest kid on the block when it comes to aquarium heaters. Consisting of a heating block that is made to fit in the filter, it heats the water as it passes through. The benefit is that no equipment is placed inside the tank, thus making this type athletically appealing. However filter heaters are rather pricey, and not always easy to find.

Once you've chosen your heater type, you should calculate the wattage needed to keep your tank at the optimum temperature. The heater guide and how to calculate heater size links will help you come up with exactly the right size heater for your needs.