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Best Aquarium Heaters of 2020

Want to make sure your fish thrive in your aquarium? Keep the temperature consistent and choose the best aquarium heater from our review.

Best Aquarium Heater Reviews of 2020

Catalina RF-1000T

Catalina RF-1000T 1000-Watt Titanium Aquarium Heat Controller

For very large aquariums

An inspired choice of materials ensures quick heat conduction and resistance in saltwater.

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1 Catalina RF-1000T Review

The Catalina RF-1000T is no doubt one of the best aquarium heaters on the market, ideal for large aquariums from 150 to 400 gallons but less suitable for small and medium-sized tanks.

The greatest feature of this heater is perhaps the titanium tubing that ensures fast heat conduction but also resistance to corrosion. This makes it suitable to use in saltwater, while the unit also resists well to pH fluctuations.

A built-in temperature sensing switch cuts off the power if the heater is exposed to air during the heating process, prolonging the unit’s lifespan.

Operating in a range from 72 to 93°F and built for submergible mounting, the Catalina RF-1000T makes an excellent choice for your large fish tank.

Best value
Aqueon Pro

Aqueon Pro Adjustable Heater

Best for most aquariums

Five available versions and a very accurate electronic thermostat make this fish tank heater ideal for most users.

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2 Aqueon Pro Review

The Aqueon Pro is one of the most versatile aquarium heaters. It comes in five power options, from as little as 50 watts to 300 watts, and responds to the demands of most users.

It suits smaller and larger tanks and boasts a wide temperature range that adjusts from 68°F to 88°F.

Fully submersible, the heater is also equipped with an electronic thermostat that provides ultra-accurate measurements to plus or minus 1°F. An auto shut-off function keeps your fish safe if the unit overheats and also prolongs the heater’s lifespan.

When it cools down, the heater starts automatically, maintaining a constant temperature of the water.

Multiple size choices, a broad temperature range, and reliable safety features make the Aqueon Pro the best aquarium heater for the money.

Also great
Cobalt 31004

Cobalt Aquatics 31004 Neo-Therm Heater

Very flat design

Shatterproof and fully submersible aquarium heater is ideal for smaller tanks.

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3 Cobalt 31004 Review

The Cobalt Aquatics Neo-Therm makes a great alternative to our best-value pick if you’re looking for a reliable heater in the 50-100 watts range.

Although coming in only three wattage options and despite its heftier price, this aquarium heater offers better temperature control, with heat ranging from 66°F to 96°F and an accuracy of only plus or minus 0.5°F.

A convenient LED indicator shows both the temperature of the water in the tank and the set temperature, allowing for quick control of the parameters.

An integrated thermal protection circuit ensures safety and reliability, turning the unit off if it overheats. Ideal to use in terrariums, freshwater, and saltwater, this aquarium heater withstands all demands.

Best budget
Tetra HT

Tetra HT Submersible Aquarium Heater

Budget fixed temp heater

Two power options make this affordable aquarium heater perfect for tanks between 10 and 30 gallons.

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4 Tetra HT Review

Compatible with almost all aquariums between 10 and 30 gallons, the Tetra HT is a reliable option for the amateurs shopping on a budget.

The heater comes in 50-watt and 100-watt options and doesn’t have an adjustable temperature feature.

Instead, it comes equipped with a built-in thermostat set to maintain the temperature in the 78°F range, which is ideal for most tropical fish.

A red/green indicator light allows you to check whether the unit is heating or not; furthermore, an overheat shutoff protection keeps you and your fish safe in case of an electrical short circuit.
Cheap and ideal for a small tank, the Tetra HT could be the right aquarium heater for beginners.

1. When to use an aquarium heater?

Many novice fish breeders and amateurs believe an aquarium heater is only useful when growing tropical fish. But even if cold water fish withstand water at room temperature, they can only thrive in water kept at a constant temperature.

The environmental temperature is subject to fluctuations, and a sudden drop of even 1°F in the temperature of the water can compromise the health of your pets. Some species are more resistant than others, but in broad terms, too many temperature fluctuations can easily eradicate the entire population in your tank.

An aquarium heater, therefore, serves two major purposes:

  • Heating water above room temperature for tropical fish.
  • Keeping water at constant temperature, either for cold water or tropical fish.

2. Types of aquarium heaters

Essentially, there are six types of aquarium heaters:

  • Hanging heaters: Are the most common and the most inexpensive type. They often come as part of aquarium kits for beginners and are very easy to install. In fact, you only have to hang them on the edge of the tank, as their name implies. They consist of a submersible glass tube and an aerial head, which may require you to cut an opening in the hood of the aquarium. Most hanging heaters are inappropriate to use in saltwater.
  • Submersible heaters: Are designed to be fully immersed in the water, a design feature that increases both their efficiency and safety. They can be positioned either horizontally or vertically and at any height in the water, as long as you mount them on the tank’s wall with suction cups. Most models come with built-in thermostats that regulate water temperature accurately. It is not recommended to mount these heaters on the gravel, as the glass could shatter.
  • Substrate heaters: Are perhaps the least popular and consist of a coil or wire grid which must be buried in the gravel or aquarium substrate. This type of heater doesn’t warm up the water, but the substrate, which then radiates heat into the water. These models are also equipped with thermostats and are particularly suitable for the tanks which contain many plants.
  • Filter heaters: Come integrated into aquarium filters and heat water during the filtering process. These heaters offer a great solution for the smaller tanks in which a submersible or hanging heater could take up too much space.
  • Sump heaters: Like the filter heaters, these ones come integrated into the sump of a trickle filter and ensure a safer environment, as they are harder to get damaged by a fish or when the aquarium is cleaned.
  • In-line heaters: Are self-contained external heaters that work in tandem with a water pump which moves water through them, getting it warmed up. Some in-line heaters don’t necessarily require a flow of water and can also be used to heat the environment in a terrarium.

3. Aquarium heater power & wattage

Size matters when it comes to aquarium heaters. A too small heater size will be incapable of warming the water in a large tank; likewise, a too large heater size can transform your aquarium into a boiling pot.

Options range from small 25-watt units to 1,000 watts. The heater must match the size of your tank. Otherwise, it could be ineffective.

How many watts does your aquarium heater need?

Experts advise calculating a power between 2,5 and 5 watts per gallon of water when choosing the best aquarium heater. To make things easier, check the chart below for the most common sizes:

Aquarium size

Heater power

10 gallons (40L)

50 watts

25 gallons (100L)

125 watts

50 gallons (200L)

250 watts

100 gallons (400L)

500 watts

200 gallons (750L)

1,000 watts

400 gallons (1500L)

2,000 watts

4. The Best Aquarium Heaters in 2019 & 2020

5. Aquarium heater placement

Depending on the size of the tank and preference, you can place the heater either at the side of the tank or in its middle. Perhaps the best place for your heater is near the water inflow and outflow, to maximize its efficiency.

Heater placement considerations

There are also a few other things to account for when choosing the right location.

  • Make sure you leave enough space between the heater and other surfaces. Otherwise, the fish could get caught between the heater and other elements.
  • Make sure your submersible heater is not touching the gravel or substrate. This could cause a gradient temperature in the heater which could shatter its glass, exposing your fish and yourself to severe injury or death through electrocution.
  • Ensure there are plenty of hiding spaces for your fish, so they won’t be tempted to hide behind the heater.
  • Before turning on your heater for the first time, keep it in the tank for at least half an hour to avoid exposing the unit to sudden temperature changes that could shatter the glass.

6. Fixed vs. adjustable temperature heaters

Aquarium heaters can have either a fixed or adjustable temperature. Most fixed temperature heaters are designed for tropical fish tanks in general, warming water to temperatures in the 78°F range. This temperature, however, is not suitable for cold water fish.

Some species, such as Gold Fish, Bloodfin Tetras, and White Cloud may not tolerate temperatures so high, and in this case, an adjustable temperature heater could be a better choice.

In broad terms:

  • Cold water fish thrive at temperatures from 60 to 72°F.
  • Tropical fish require temperatures between 72 and 80°F.

Passionate hobbyists and business owners would benefit most from an adjustable temperature heater which allows to adjust the temperature to suit different biotopes or to manipulate breeding.

7. What water temperature in a biotope aquarium?

Biotope aquariums recreate natural habitats for cold water or tropical fish to thrive. These aquariums typically require specific temperatures which closely simulate the real temperatures of the water in the area where your fish come from. For example:

  • Amazon biotope aquariums: Are typically populated by fish like the Peruvian angelfish and False rummynose tetra fish. These aquariums thrive at warmer temperatures in the 82°F range.
  • Reef biotope aquariums: The best thing to do is to set the water at a temperature level close to the water temperature in the area where your corals come from. For instance, Indo-Pacific and Caribbean corals have a temperature between 82 and 89°F.
  • Lake Malawi biotope aquariums: Populated with colorful Peacock cichlids and Mbuna fish, these habitats require a water temperature between 72 and 82°F.

8. What other features to consider?

Besides all the above, the best aquarium heaters come with a series of other features that add safety and ensure a smoother operation.

  • Perhaps the most important feature is a thermostat designed to keep water temperature constant.
  • Invest in an aquarium heater that is easy to maintain and clean.
  • An overheat shutoff function helps save your fish if the unit overheats and also prolongs the unit’s lifespan. An automatic restart when the heater cools off also ensures all its functions are reassumed in a timely manner.
  • Also, check the materials the heater is made of. Choose one that is resistant to corrosion and pH fluctuations.
  • An indicator light lets you know whether the unit is heating the water or is in standby. Some of the best aquarium heaters indicate both the temperature in the water and the set temperature, allowing for a better control of the parameters.

9. The Best Aquarium Heater for the Money

Best value
Aqueon Pro

Aqueon Pro Adjustable Heater

Best for most aquariums

Five available versions and a very accurate electronic thermostat make this fish tank heater ideal for most users.

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