Where to Place an Aquarium Heater For Maximum Efficiency

Where to Place an Aquarium Heater For Maximum Efficiency 1

You want to warm up your fish tank but are not sure where to place your aquarium heater.

This is a challenge that a lot of aquarium hobbyists often encounter. And the fact that you are reading this article means that you are also experiencing some challenges with this. 

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Why Do You Need An Aquarium Heater?

This is simply a piece of aquarium equipment that is used to warm up and keep your aquarium’s water warm; it prevents the aquarium temperatures from going below a certain point. It works by converting electricity into heat. 

There are different kinds of aquarium heaters; external (heating element is outside the tank) and external heaters (heating element is inside the tank). External heaters are available in two types; in-filter and in-line heaters. Internal heaters are available in three types; substrate, submersible, and hanging. 

You will need this equipment for your fish tank if the temperature in the room that is housing your aquarium is below the recommended temperature for your fish. You will also need one if the room temperature ever falls the minimum temperatures safe for your fish.

Given that the majority of aquarium fish available for sale are tropical, an aquarium heater thus becomes a necessity for most home aquariums. Not unless you reside in a tropical region, you’ll certainly have to purchase a heater. If not, your fish will eventually die either because of the extremely low temperatures or from weekend immunity.

How and where to position a heater in your aquarium

There are different ways of getting this done. Let’s take a look.

Horizontal position

You can place your heater horizontally, at the back of your tank, and just a couple of inches above the gravel or substrate. Placing your heater low and horizontal to the ground has some benefits.

First, placing your heater low allows for better dispersal of heat around your tank; remember, heat rises. Also, apart from covering a wider region, positioning the heater low and horizontally makes it easy to hide and blend your heater with the design of your tank.

Another benefit is that you will not have to keep on switching your aquarium heater off and on during partial water changes since your heater will be constantly submerged in water. 

Vertical position

This is another possible way of positioning your heater in your aquarium. Also, for tall and slender fish tanks, this is probably the only option.

If you choose to place your heater vertically, it is advisable to position it next to the filter pump, normally at the back corner of your aquarium. This way, the filter intake will suck up the warmed up water and distribute it back in the tank, or the filter outlet is pouring water past over heater, moving warm water around your tank.

Two heaters on opposite ends

For small fish tanks in homes that are not really cold, the heater’s size should be five watts for every gallon of water. A twenty-gallon fish tank should this have a 100-watt aquarium heater.

Fish tanks with a capacity of 40 gallons and above should have two heaters positioned at opposite ends; Instead of a single 200-watt heater, go for a 100-watt aquarium heater at opposite ends. This will ensure uniformity in water temperature all over the tank.

The best part about having more than one heater in your tank is that they help out each other. Given that the heating job isn’t left to only one of them, the chances of wearing out are low.

Another benefit is that they act as back-up for each other. In case one of the heaters die, your aquarium will at least continue staying warm thanks to the other heater.

All in all, experienced aquarists recommend placing your aquarium heater close to the area with the greatest flow of water, for instance, the outlet from your filter pump. Position the aquarium heater horizontally above the gravel close to the filter outlet. Having water continuously flowing over the aquarium heater is what rapidly and evenly spreads the heated water all over the fish tank.

After positioning your heater, there are a couple of factors that you need to consider in order to ensure that your aquarium’s water temperature is both stable and adequate for your tank’s inhabitants. These include:

  • The fish species you’ve stocked in your tank

Certain fish species such as guppies, bettas, neon tetras, and angelfish prefer their water to be warm at all times. Others, however, like swordtails and barbs are hardier and are capable of tolerating some changes in their water temperatures.

  • The size of your tank

Those hobbyists with huge tanks might have to install two smaller aquarium heaters in order to ensure water warming. These heaters should be placed on opposite ends of the aquarium for proper and uniform heat distribution.

  • The number of aquarium heaters

Most aquarists recommend the use of more than a single heater if you decide to use either a submersible or hang-on heater for your aquarium. Having more than one aquarium heater ensures that there is back-up just in case one malfunction. This, in turn, ensures that your aquarium’s inhabitants do not get shocked by drastic water temperature changes.

Tropical fish species are especially more susceptible to water temperature changes. If the temperatures change by even just a few degrees for a while, this could result in problems for such fish.

  • Your heater’s tube

It is important to ensure that the length of the heater’s tube matches the length or height of your tank. Remember that heat rises, and so you have to ensure that you are indeed covering the entire depth of your tank.

  • Your tank’s positioning

Is your fish tank housed in a small cozy room or a massive room that’s difficult to keep warm? Is it next to a window that receives direct sunlight, making it warm at daytime but then things get cold at night? Is it below or close to an air-conditioning opening that may cool it a lot? All these are things are capable of affecting your aquarium’s water temperature stability.

How is heat distributed in an aquarium?

There are three styles of heat distribution in an aquarium. These are conduction, convection, and circulation.

  • Conduction

It refers to the distribution of heat from hot regions to cold regions in order to achieve thermal equilibrium. When your tank’s water is heated, water molecules acquire kinetic energy and start moving around more. It is this energy that is spread all through the water as heat. However, given that water is only a moderate heat conductor, most of the heat distribution in your aquarium is achieved through convection and circulation.

  • Convection

Convection takes place when water becomes less and less dense and ascends to the top as it warms up, resulting in the formation of conventional currents. In this case, the heater warms the water surrounding it, and this water ascends to the top of the tank and displaces the cooler water, which is denser hence it sinks.

  • Circulation

Your aquarium’s main style of heat distribution will come from the circulation of water with the help of your filter pump. Your filter will, ideally, thoroughly mix the water and prevent any cold or hot parts from persisting in your fish tank.

Choosing the right heater for your aquarium

Experts recommend having completely submersible heaters rather than those that are only partly submersible. This leaves you with more placement freedom for whichever heating position the present situation calls for. However, if your aquarium heater is only partially submersible, place an airstone beneath it to help in drawing up the cool water to the heater.

Submersible heaters can be completely dipped in the tank water making them more efficient than hanging heaters. Submersible heaters can be placed horizontally, vertically, or even at an angle. They, however, tend to function when placed either horizontally or vertically.

Submersible heaters with internal thermostats are normally more efficient when horizontally positioned in the aquarium, and somewhat low in the tank’s water column. This helps the thermostat to obtain accurate readings on the water temperatures and correctly activates and deactivates the aquarium heater.

A clip featuring suction cups is normally used to attach submersible heaters to the back of the aquarium. It is crucial to ensure that the heater is kept off gravel as the heat conductivity difference between the gravel and water could cause the heater’s glass to crack. Also, ensure that ample space is left between the aquarium heater and the tank’s side or gravel to make sure that none of your fish gets caught against the aquarium heater and gets burnt. 


Tammy Slater

Tammy Slater is the founder of arew.org, a home and garden blog that provides inspiration and resources for homeowners and renters alike. A self-taught DIYer, Tammy loves nothing more than tackling a new project in her own home. When she's not blogging or spending time with her family, you can usually find her rooting around in the garden or at the hardware store.

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