The Importance of a Fish Tank Heater

fish tank heater

When setting up an aquarium, there are many aspects to keep in mind.

Between the plants, the gravel, the filter, and lighting, there are an abundant amount of decisions to make and lots of choices.

However, one important item that sometimes gets overlooked is the fish tank heater.

Different fish require different temperatures so make sure you research the needs for the particular varieties you decide on.

Turn It Up

Fish typically need water temperatures of 80 degrees or higher; in order to reach and maintain these temperatures, a water heater is necessary.

Just like tanks come in many different shapes and sizes, aquarium heaters come in a wide range of sizes with an assortment of features and at a variety of price points.

One of the most important aspects of aquarium water temperature is STABILITY.

As a rule of thumb, water temperature should not change more than a couple of degrees on a daily basis.

A stable heater that can maintain a constant water temperature is a must.

Types of Heaters

  • Submersible Heaters
  • Hanging Heaters
  • External or Inline Heaters

Submersible Heaters

Finnex Ray2 Aquarium LED Daylight

Just as their names say, submersible heaters lie below the water level in your tank.

Generally speaking, submersible heaters must stay submerged or they risk damaging their heating element.

Keep this in mind whenever you plan on changing the water or moving the heater or tank.

These types of heaters are commonly placed beneath the aquarium’s filter output, heating water as it enters the environment.

This method keeps a steady stream of heated water circulating within the tank.

One recommended submersible heater would be the Quartz Glass Submersible Heater by ViaAqua.

This particular heater even has a built-in thermostat and a visible temperature setting for a better experience.

The price is very affordable considering the number of positive reviews the heater has received.

Hanging Heaters

Hanging heaters are designed to hang over the side of the tank similar to the way a filter hangs on the side of the tank.

The heating element itself obviously hangs on the inside of the aquarium.

The controls for the heating apparatus are situated on the portion that sits outside the tank for easy access.

Similar to the submersible heaters mentioned earlier, make sure to keep the water level higher than the heater so as not to damage it.

External or Inline Heaters

External or inline heaters are attached downstream from the water pump, which is located outside of the aquarium.

Water is pumped into the filter then into the water heater, so the clean water is heated before it enters the aquarium environment.

These fish tank heaters are especially useful if you have live plants in the tank that might spread onto the heater causing it harm.

Overly aggressive fish might also try to take a bite out of your heater, so an external heater will keep it protected.

External heaters are also known to be more accurate, keeping your water temperature steady. You can get a quality inline heaters cheaply on Amazon.

Installation and Use

All heaters, regardless of their position relative to your tank, have different controls.

Make sure to read the manual that comes with your heater prior to using it for the first time and definitely before adding fish to your aquarium.

Many internal heaters come with suction cups that will adhere to the side or bottom of your tank but check the packaging for this information before you buy.

If they do not come with the proper installation hardware, make sure you purchase it separately.

Some heaters come with integrated temperature gauges to keep an eye on the temperature in the environment.

Again, if this hardware is not included in your heating solution, pick up a separate thermometer before you leave the pet store.

Allow plenty of time for your aquarium water to heat up prior to adding fish, so that the glass and water can obtain similar temperatures and prevent the glass from breaking.

Pick the Proper Heater

A common guideline for selecting a fish tank heater is to choose one that can output 3 to 5 watts of power per gallon.

The wattage of the heater determines the capability of the unit’s ability to heat and maintain the temperature within the aquarium.

For example, a 29-gallon aquarium using a 29-watt heater would equate to 1 watt per gallon, which is not enough to maintain a suitable temperature.

For energy conservation, using two smaller heaters is recommended over one higher powered one.

Hope this post is useful for you. I would appreciate it if you can share this with anyone who you think might find this article useful too!

Drop a comment below with any questions that you might have or share your personal experience. Thank you.

1 thought on “The Importance of a Fish Tank Heater”

  1. I’ve used hang on heaters in the past and I have to say, I would never recommend someone use them. Especially now that submersible heaters exist, there is no point in having something that could shatter if your water level drops too low.


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