How to Choose an Aquarium Heater

How to Choose an Aquarium Heater

A stable temperature is one of the most crucial elements in a healthy aquatic environment. Most corals, fish, and invertebrates cannot tolerate either too low or too high temperatures. An appropriately sized aquarium heater will keep the system’s temperature stable and prevent it from falling below optimal levels.

What is a Heater?

An aquarium heater consists of a heating element inside a glass, plastic, or titanium case capable of raising the water temperature within the tank. Most heaters feature a built-in thermostat and can maintain the temperature on the tank within 1-2 degrees. Heaters come in a variety of shapes, sizes, and power outputs.

What is the Ideal Tank Temperature?

The ideal temperature will depend on the type of livestock.

General Recommendations

  • Reef Aquariums: 75-78 degrees Fahrenheit; corals love stability, so pick a specific temperature and minimize fluctuations.
  • Saltwater Fish Only Aquariums: 75-82 degrees Fahrenheit; fish are more tolerant to temperature changes than corals; however, minimizing temperature changes is still important.

Types of Aquarium Heaters

Aquarium Heater Comparison
Aquarium heater options

Most aquarium heaters are either glass, plastic, or titanium, and all three are suitable options for a reef aquarium. Here is a breakdown of the benefits and drawbacks of each type.

Budget Glass options are generally the least expensive, followed by plastic.
Power Titanium heaters pack more power than glass or plastic heaters, making them the preferred choice for tanks over 250 gallons.
Efficiency The type of heater does not significantly impact the heater’s efficiency.
Durability / Safety Unlike glass, titanium and plastic heaters won’t shatter or crack.
Controllability Titanium, plastic, and glass heaters can be monitored and controlled with a controller.
Aquarium Heaters Comparison Chart

Where to Place an Aquarium Heater

While this may sound like an easy decision, it can vary depending on the type of filtration.

General Recommendations

  • Sump Filtration: Place the heater either vertically or horizontally in a high flow area of the sump.
  • All-in-One Filtration: Place the heater vertically in the main filtration section.
  • Hang-On the Back Filtration: Place the heater vertically within the display.
Aquarium Heater Placement
Aquarium heater placement options

Sizing an Aquarium Heater

The proper heater size will be impacted by (1) the total water volume, (2) the ambient room temperature, (3) other heat inputs, like a large pump, and (4) the target temperature. Lastly, It is also critical that the heater physically fits into the space you have.

General Recommendations

  • For tanks less than 55 gallons: Use 5 watts of heater for every gallon.
  • tanks over 55 gallons: Use 3 watts of heater for every gallon.
  • For aquariums over 25 gallons: Use two or more heaters. Multiple heaters provide an additional layer of protection if one heater fails.
  • Make sure the heater fits the space.


Heaters are another essential tool in creating an ideal environment for aquatic life, so we do not recommend saving a few bucks by purchasing a used heater or one of poor quality. When your heater is operating correctly, you shouldn’t think about it. Still, that one time you have a heater fail, you will wish you had invested in a high-quality unit. Invest in a temperature controller that will automatically turn your heater on and off as required for an added layer of protection.

With the proper heater selected, you should be able to keep a consistent temperature within your display tank. Dialing in the appropriate temperature within your aquarium will allow you to shift your focus towards some of the other details that must be kept in check.

If you still have any questions on how to choose an aquarium heater for your system, or you are seeking a recommendation, please contact our support team.

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