Can Aquarium Heaters Be Used Out Of Water? Which Ones Can Be?

Image of an aquarium with a heater outside it

The most common aquarium heaters you find are the ones that are installed inside the tank. But can aquarium heaters be used out of water?

External aquarium heaters like in-line heaters can be used out of the water as they are specifically designed to work outside. However, internal heaters like submersible, immersible, and substrate heaters can’t be used outside the water as there’s a risk of explosion or the glass getting shattered.

Having said that, let’s see where different types of heaters are placed.

Types Of Heaters And Where They Are Placed

There are various types of heaters available in the market, both internal and external.

Internal filters are those that have the heating element placed inside the tank, while external filters are those that have the heating element outside the tank.

Following are the types of aquarium heaters and where they are placed.

1. Submersible Aquarium Heaters

As the name suggests, submersible aquarium heaters are entirely immersed in the water.

They are usually attached to the back of the aquarium by a clip with suction cups.

You can place these heaters deep in the water, either horizontally, vertically, or at an angled position.

It’s best to place a submersible heater horizontally if it has a thermostat inside it.

This helps to get the most accurate water temperature reading.

Also, it’s crucial that the heater doesn’t touch the gravel or substrate.

There should be enough space between the heater and gravel for the safety of the tank inhabitants.

Furthermore, ensure that fish don’t get caught in the heater. Otherwise, it can prove fatal.

2. Immersible (Hanging) Aquarium Heaters

Immersible aquarium heaters are also known as Hanging heaters.

These heaters are widely used and are the least expensive. Moreover, you also get them with most aquarium kits.

You can hang this heater at the back of the aquarium on its top edge.

It has a glass tube containing the heating element, which is set in the water.

Most aquarium hoods have a section that you can cut to accommodate the hanging heaters.

If a hood doesn’t have a section, you need to cut an opening in it to accommodate the head of the heater.

Furthermore, you need to secure the hanging heater so that it doesn’t knock and break the glass.

If these heaters aren’t installed correctly, there’s a risk that the glass sheath can break and injure the fish.

Moreover, there’s a possible risk of fire too.

Also, make sure that the glass tube is not touching any other part of the aquarium.

If it touches anything else, it can create a hot spot that can be fatal to the fish.

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3. External Aquarium Heaters

An external aquarium heater is more like a sturdy pipe that contains a heating element inside it.

Additionally, it contains a built-in thermostat that automatically switches off once the preset temperature is attained.

An example of an external aquarium heater is an In-line heater that requires a water pump for circulation.

This filter works in conjunction with a canister filter or a trickle filter.

The water is pumped out from the tank through a tube into the heater.

The water then gets heated, and the warm water is returned to the tank.

One of the most significant advantages of in-line heaters is that the heated water is evenly distributed throughout the tank.

Also, you need not turn them off while performing a water change.

Besides, they are suitable for small tanks where space is a constraint.

4. Substrate Aquarium Heaters

Aquarists usually don’t use substrate aquarium heaters. These heaters are buried inside the aquarium substrate or gravel.

The heater contains a wire or coil in an insulator that acts as the heating element.

The wire becomes hot when the heater is switched on. It then heats the substrate or gravel in the aquarium.

The heat thus created is then radiated from the substrate to warm the aquarium water.

Once the water becomes warm as per the set limit, the thermostat will switch the heater off.

These heaters are particularly beneficial for planted tanks.

Since the substrate acts as an insulator, the plant roots buried inside it don’t get too cold.

5. In-Sump Aquarium Heaters

In-sump aquarium heaters are also known as sump heaters.

They are just like a submersible heater set up in the sump of a trickle filter.

In-sump aquarium heaters are safe as the chances of the fish getting caught under the heater are less.

Also, the risk of fish getting injured by dashing on the heater is minimized with these heaters.

6. In-filter Aquarium Heaters

In-filter aquarium heaters are inside the filter and are hence called in-filter heaters.

These filters work by heating the water that is passing through the filter. The heated water is then returned to the aquarium.

One of the biggest advantages of an in-filter aquarium heater is that it saves space.

Another advantage is that the water gets cleaned and heated simultaneously.

Moreover, the warm water is distributed evenly in the tank when it flows into the aquarium through the filter.

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Why Can’t Aquarium Heaters Work Outside?

An external aquarium heater, like an in-line heater, can work outside.

However, most heaters are placed inside the tank as they are designed to work inside the aquariums.

The primary function of aquarium heaters is to maintain a constant temperature in the aquarium.

They do this by circulating hot air through the aquarium and then releasing it.

This way, the water temperature remains consistent throughout the entire tank.

If the internal aquarium heaters are placed outside the tank, they will run continuously without heating the water effectively.

Also, internal aquarium heaters are designed in such a way that some of their parts need to be covered by water to avoid damage.

Since they are not meant to function outside the water, there’s a high risk of damage and accidents if they are used outside the water.

What Happens If A Submersible Aquarium Heater Is Used Out Of Water?

Submersible aquarium heaters need to be placed inside the water to avoid damage.

If they are placed outside, they will overheat extensively. This can melt the heaters and also shatter the aquarium glass.

Moreover, submersible heaters can crack if they are turned on out of the water.

In worst cases, when they are placed outside of the water, it can cause damage to the electrical connections and cause a short circuit.

In addition, fire sparks can fly out, which can be fatal.

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Should An Aquarium Heater Be Fully Submerged?

The majority of the aquarium heaters are fully submersible.

However, whether a heater can be fully submerged depends on the type of the aquarium heater.

Internal aquarium heaters are installed inside the aquarium tank and use a heating element to provide heat.

You can place these types of heaters in any position inside the tank as long as there’s enough space for the heating element.

Submersible internal heaters can be fully submerged in the water.

On the other hand, external aquarium heaters are the ones that can’t be fully submerged in the water.

The best examples are in-line aquarium heaters that work along with canister or trickle filters.

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