6 Best Aquarium Heaters – Ultimate Review for 2021

2 gold fish swimming in fish tank with one of the best aquarium heaters

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This is a review of 6 of the best aquarium heaters.

Our top pick for the best aquarium heater is the Fluval E Electronic Heater (Fluval E200). Keep reading or view the product to find out why, as well as find other great options!

Fluval E300 Advanced Electronic Heater, 300-Watt Heater for Aquariums up to 100 Gal., A774
  • Aquarium heater with dual temperature sensors provide accurate and real-time water temperatures
  • LCD temperature display available in both Fahrenheit and Celsius; with a range of 68 to 93 degrees Fahrenheit
  • Fast heat technology built with a safety shut-off and integrated fish guard to protect fish and invertebrates
  • Equipped with a slim profile mounting bracket and colored display alert system

Last update on 2022-01-20 / Affiliate links / Images from Amazon Product Advertising API

We all want to keep our fish healthy and happy.

That is why we need the best aquarium heater possible.

Your aquarium heater is one of the most important pieces of equipment you will purchase as an aquarium enthusiast, so spending time to research the best heater to fit your fish environment will ensure your money is well-spent.

Without the right heater, you may find that your fish have difficulty in maintaining their body temperature, which can lead to problems with health and reproduction – not something any fish owner wants!

With so many different types, it can be tricky to know which one is right for you.

To save you time, we did the heavy lifting for you and completed extensive research so you can choose the best aquarium heater that is best suited for your personal fish environment.

Here are the reasons we love the Fluval E Electronic Heater (Fluval E200) and think you will too:

  • Dual temperature sensors create extreme accuracy in real-time
  • Digital (LCD) display for heating mode and standby mode
  • Heat range of 68 to 93 degrees Fahrenheit
  • Alerts you if there is a serious temperature problem in your tank
  • Has an integrated fish guard to protect your fish from the heating element
  • Comes in various sizes of E heaters to meet your aquarium size needs
  • 5-year warranty

Other Heaters Included in this Review

We know you’re excited to jump into the details about the best heaters so you can pick one out. However, we want to be sure you are getting the one that is the most suitable for your aquarium life.

For that reason, we have included the information you need to make the best selection.

If you have already completed your research and you are here to simply read our recommendations, here are the other heaters we have included.

You can check the price and details on Amazon by clicking on the heater you are interested in or hop on down on the page a bit and you will find the full details of each review.

Do You Need an Aquarium Heater?

It is important that you use an aquarium heater to maintain the proper temperature range for your fish, considering your fish need help to regulate their body heat.

Before you start comparing the best aquarium heaters to find one suitable for your fish tank, be sure the water temperature needs to be regulated.

This will depend on the type of fish you plan to put in your aquarium.

For example, white cloud mountain minnows, dwarf freshwater shrimp, and goldfish (just to mention a few) are perfectly happy in a tank without a heater because they are considered cold-water fish. They easily thrive living in a tank of room temperature water.

However, this is not common for most fish that are popular for aquarium enthusiasts. The typical aquarium fish are tropical fish that need water temperatures ranging from 75-85 degrees F (24-28 degrees C).

If they are put into a water temperature range less than this, it is too cold and they will not survive.

For these reasons, you need to have a plan in place for the kind of fish you will be putting into your aquarium so you know if you will need to purchase a fish tank heater to maintain the proper water temperature for them.

How to Choose the Best Aquarium Heater for Your Tank

closeup shot of a Redhump Eartheater fish swimming in an aquarium

While things such as a year warranty or lifetime warranty are important, it is more important to get a heater that will give your fish a happy and healthy environment to live in.

The most common problem fish pet owners have with their new aquariums is getting them too cold because they didn’t think about how many watts were needed and what size heater was appropriate before purchasing one.

When reviewing the best aquarium heaters, it is important to understand the details so you make the best decision.

The first step is to understand how the wattage of the heater impacts the water temperature based on aquarium volume (size.)

Wattage in Relation to Aquarium Volume (size)

Choosing the right size heater is the first step in selecting the best aquarium heater for your tank.

Aquarium heaters come with various levels of power. The power levels are defined by wattage, the higher the wattage level the more powerful the heater.

If the heater is not powerful enough, it will have low wattage which could either lead to dangerous water temperatures (hot or cold) in your tank or cause your heater to constantly run and quickly wear out.

If the heater is too large, the high wattage could lead to overheating and an increased chance of the glass cracking, the water overheating, or dangerous swings in the water temperature.

The common rule among aquarists is that the wattage range should be between 2.5 and 5 watts per every 1 gallon of water, with 5W being the recommended wattage as long as you are using an aquarium lid to hold in warmth and prevent evaporation.

More wattage may be necessary depending on how much you need to increase the water temperature.

If you are using two heaters, the total heating capacity of all units should be equivalent to the wattage that is required for the correct temperature.

The chart below provides a great visual you can keep handy as a reference:

chart showing the recommended wattage variables vs. room temperature for aquarium heaters

PRO TIP

When determining room temperature, be sure to consider the location of the room where you house your aquarium.

Whenever possible, it is best to put your aquarium in a location where room temperature is fairly consistent year-round.

Questions to consider that can affect the water temperature:

  • Does the room have direct sunlight streaming in all day making the room hotter than other areas of the home?
  • Is the room in a basement, which is cooler than other areas of the home?
  • Does the aquarium sit next to or close to an air conditioner or fan?
  • Does the room have sunlight streaming directly into a window towards the end of the day so the room is cool in the morning and overly warm in the afternoon?
  • Is there a large fluctuation in room temperature over the course of a year with changing seasons?

What Fish are You Putting in Your Aquarium?

To make the best selection, you also need to know what will be going inside your tank.

If you plan on having plants that require low-light conditions or fish that prefer a warmer water temperature, you need to prepare and purchase the correct heater to meet their survival criteria.

For example, the African Cichlid prefers temperatures between 77°F – 85°F while goldfish can live in water temperature up to 68°F.

These two types of fish would be incompatible with each other so make sure all the fish you will be putting in your aquarium live under similar environmental parameters before you make the purchase.

Final Considerations Before Choosing the Heater Best-Suited for Your Tank

Using the volume size of your tank, knowing the room temperature where you will put your aquarium, and alongside the above considerations, you are ready to determine what size heater your need.

The final step is determining how many degrees you need to raise your aquarium water temperature above room temperature.

For example, if your tank is 20 gallons and the room temperature it’s in is 70 degrees F (21 degrees C), you need a 60W heater.

However, if the tank water temperature needs to be 75 degrees F in this same room that is 60 degrees F (16 degrees C), a stronger heater would be necessary because this is a much larger gap between your room temperature and aquarium temperature. In this case, a 100W heater would be a much better choice.

PRO TIP

  • If you are unsure of the volume size of your tank, look at the label on the side of your aquarium.
  • If you are unable to locate the label, use the Aquarium Tank Volume Calculator. 

Note: If you manually figure your tank volume, remember the inside of the tank is the water volume, not the outside.

Importance of Using the Correct Aquarium Heater

Selecting the correct heater is essential, and there are many factors to take into consideration.

It is important to use the correct type of aquarium heater because not all types of fish are the same. For example, some need warmer water than others, and some even require a different temperature range in different seasons.

Different Kinds of Aquarium Heaters

multiple fish various colors under vivid blue water

Before you start narrowing down the aquarium heater to actually make a purchase, you need to determine the style and type of heater you need (or want.)

Choosing the best heater depends on the size of your tank and the species of fish you are keeping, as well as personal preference.

You can choose from an external aquarium heater or a submersible aquarium heater.

External heaters use water from inside the tank as part of their heating process. They typically need more space outside the tank.

Just as the name indicates, submersible heaters sit below the surface. They don’t require any additional room outside of the tank. They are also the most commonly purchased because of their low cost, ease of use, and reliable performance.

The type you choose really depends on what your needs are for your fish and their habitat requirements.

Some people may need more than one kind to provide adequate water temperature throughout the year for different seasons.

Hanging/Immersible Aquarium Heaters

An immersible heater mounts and hangs over the edge of your tank. For this reason, it is often referred to as a ‘hanging’ heater.

The heating element in the immersible aquarium heater is typically encased in a glass tube and sits at the top of the water to heat the tank, applying heat from the top down.

While not the most commonly purchased, this heater is the most commonly used because they are often included in the starter pack box for beginner freshwater tanks.

You’ll need a hole in the hood of your tank to allow this heater to sit over the top of it.

Also, it is important to note this type of heater is usually less efficient but it does provide basic heating. Immersible heaters are not recommended for brackish or saltwater setups.

Pros

Cons

  • Less expensive than other heaters
  • Included with most starter tank kits
  • Doesn’t keep the temperature of the water as consistent as a submersible heater
  • You have to alter the lid of your tank, making it difficult to open or move

Submersible Aquarium Heaters

Fully submersible heaters are the most popular when people are ready to replace the typical starter kit heater.

They are placed inside the fish tank under the water surface next to the inlet of the filter, allowing them to quickly and easily regulate the water temperature.

These heaters are popular because they hold a more stable and consistent temperature in the fish tank than the hanging heater.

Another helpful feature on most submersible heaters is they have an LED display so you can visually see the heater is turned on.

Another favorite key feature is their ease in setting up.

The combination of high performance and user-friendliness is what makes them the type of aquarium heaters purchased most often.

Pros

Cons

  • Keep water temperature controlled more efficiently than an immersible heater
  • Easy to set up
  • LED light for power off/on in most
  • Cost more than an immersible heater

In-Line Aquarium Heaters

The in-line heater works differently than either the submersible heater or the immersible heater.

Rather than heating the water inside the tank, the in-line heater is placed in the sump or between the sump and filter. As the water flows by this area, it is heated on the way back to the tank.

Aesthetically speaking, many people love that their tank doesn’t show additional equipment but is instead tidy with their fish as the focal point.

Pros

Cons

  • Nothing inside the tank to create stress for your fish
  • Aesthetically pleasing because you can’t see the heater
  • More expensive
  • Higher risk of a leak because all equipment is outside the tank

PRO TIP

The in-line heater is the best choice for aquarists that keep larger aggressive fish known to fight with tank equipment (such as some cichlids.)

They tend to be much higher priced and because the components are outside the tank there is more risk of a leak than the other heater options; however, they are less easily damaged so you save money by not having to replace them.

Substrate Aquarium Heaters

These heaters were widely popular in the 90s, typically in tanks loaded with aquarium plants, because they produced a gentle water movement to stimulate the plant roots and initiate quick growth.

Substrate heaters operate by starting the heat at the bottom of the tank and pushing it upward. This is done by installing wires onto the base of your aquarium.

However, they are much less popular today, likely because of the difficult installation coupled with a higher cost to purchase.

Since they can still be found today we included them in the review so you would know what you were up against if you came across one of the few still floating around in the market.

Important Safety Features You Need

boy feeding best fish food to aquarium fish

There are some things that should be non-negotiable in your quest to buy a new heater for your fish tank. Safety should definitely be on this list.

Safety features that should be included in your aquarium heater are an automatic shut-off if the temperature gets too high or the water level gets too low.

You should also look for a simple and effective way to monitor the water temperature, like an indicator light signifying if the heater is powered on or off. A heater with an LCD or LED screen you can read is another common way to monitor the water temperature.

Best Aquarium Heater Reviews

The importance of the aquarium heater is one that should be taken seriously by anyone considering purchasing this product.

To provide you with the most accurate and updated information for this review, our research was extremely thorough and time-consuming to ensure we were recommending the best aquarium heaters to you.

This is how we conducted the research:

  • Scoured forums and online communities for personal reviews, taking into consideration good reviews, bad reviews, angry reviews, and even reputable and unreputable companies so there were pages of notes on each heater to compile for the final recommendations.
  • Dug into the manufacture details for each heater to ensure any advertising information that was not on the manufacture’s website was accurate.
  • With our top selections, we sourced online communities and groups to get additional real-life experiences with the heaters from a more personal standpoint.

This stacked information gave us everything we needed to give you the best aquarium heater list possible.

We believe this deep research process is much more beneficial than completing a personal trial of each heater because hundreds of uses in different environments are much better than one short-term use in one environment.

Note: All products were available and details were deemed accurate as taken from each manufacturer at the time of the review.

The Fluval E200 Electronic Heater features dual temperature sensors and real-time water temperatures.

The Fluval E Series heaters feature VueTech technology. They monitor your water continuously and house an adjustment level to keep temperature adjustment quick and simple in precise 0.5-degree increments.

It boasts an LCD display for the temperature that shows both Celsius and Fahrenheit. The temperature range is 68 to 93 degrees Fahrenheit.

Quick Facts

Wattage options:

50W – 300W

Safety Features:

  • Change in temperature readout color if water varies +/- 2 degrees Fahrenheit from preset temperature
  • Integrated fish guard keeps fish from coming in contact with the heater core
  • Glass sleeve protects large fish species from shocks

Warranty:

5-year warranty

What fish is it best for?

  • Freshwater fish
  • Saltwater fish

Pros

Cons

  • High level of safety options to protect fish and aquarium
  • Flashing display if the temperature fluctuates by 5.5 degrees Fahrenheit from the desired temperature
  • Doesn’t have an auto shut off when taken out of the water or if the water level falls below the minimum requirement (dry sensor)
  • Internal heater tube constructed of glass
Fluval E300 Advanced Electronic Heater, 300-Watt Heater for Aquariums up to 100 Gal., A774
  • Aquarium heater with dual temperature sensors provide accurate and real-time water temperatures
  • LCD temperature display available in both Fahrenheit and Celsius; with a range of 68 to 93 degrees Fahrenheit
  • Fast heat technology built with a safety shut-off and integrated fish guard to protect fish and invertebrates
  • Equipped with a slim profile mounting bracket and colored display alert system

Last update on 2022-01-20 / Affiliate links / Images from Amazon Product Advertising API

The Cobalt Aquatics Flat Neo-Therm Heater is a fully submersible heater that features a simple-to-use ‘one touch’ control system. It boasts an advanced electronic thermostat with an accuracy rate of +/- 0.5 degrees and a broad temperature range of 66 degrees F to 96 degrees F. Any aquarist will love this wide range because they can fill their tank with pretty much any fish they want.

The design brags a modern look that is sleek and super flat so it takes up little space.

A top feature is a focus on reliability and safety, with the integrated thermal protection circuitry which will shut the heater off before any overheating occurs. The unit is also practically indestructible with the shatterproof outer casing.

Quick Facts

Wattage options:

25W – 200W

Safety Features:

  • Integrated thermal protection circuitry
  • Constructed of resin/thermoplastic with a shatterproof outer-casing

Warranty:

3-year warranty

What fish is it best for?

  • Freshwater fish
  • Saltwater fish
  • Terrariums

Pros

Cons

  • Ability to raise tank water temperature 11 degrees Fahrenheit above ambient room temperature
  • Doesn’t have a 5-year warranty
Cobalt Aquatics Flat Neo-Therm Heater with Adjustable Thermostat (Fully-Submersible, Shatterproof Design) from 25W to 300W
  • Super-flat design. Fully submersible, modern design for energy efficient Aquarium and terrarium heating. Includes reversible holster/bracket, which allows heater to face inward or outward. See the...
  • Accurate, one-touch system. Simply set temperature between 66-96°f with one touch and the neo-therm electronic thermostat will maintain Tank temperature within +0.5°F. Led displays both set temp and...
  • Ultimate safety and reliability. Integrated thermal protection circuitry prevents heater from overheating. If you forget to turn it off, the neo-therm will automatically shut it down.
  • Virtually indestructible. Unlike cheap, glass heaters, the neo-therm is a resin/thermoplastic heater with a shatterproof outer-casing. Made in Poland and includes a 3-year warranty.
  • Manufacturer You can trust. Most manufacturers rate their heaters on the ability to raise an aquarium 2-3°f above ambient temperatures. This is unreliable and misleading, as the average home...

Last update on 2022-01-20 / Affiliate links / Images from Amazon Product Advertising API

The Hygger 200W Digital Quartz Aquarium Heater features an external LED display thermostat controller and thermometer. It is a submersible heater with a black plastic guard.

The water temperature range for this heater is 61-90 degrees Fahrenheit. If the temperature rises above 97 degrees Fahrenheit there is an auto shut-off.

Quick Facts

Wattage options:

200W (Other watts for different Hygger models)

Safety Features:

  • Built-in guard to keep fish from touching the unit

Warranty:

3-year warranty

What fish is it best for?

  • Freshwater fish
  • Saltwater fish
  • Terrariums

Pros

Cons

  • Built-in heater guard
  • Standby and active mode indicator light
  • Doesn’t have an overheat sensor
Sale
hygger 200W Digital Quartz Aquarium Heater for Fresh-Water Salt-Water, with External Led Display Thermostat Controller and Thermometer, Auto Submersible Heater for Fish Tank 15-30 Gallon
  • 【Fast Heating Up】voltage 110-120V/60HZ, power 200W, US three-pin plug, heater rod length 6.3 inch, 200W submersible heater for fish tank 15-30 Gallon. The heater power cord is 6ft, the controller...
  • 【Fully Automatic Control】very easy and reliable to use. After finishing the temperature setting, the fish tank heater will run automatically by itself. It will stop heating when the water temp...
  • 【Must be Fully submerged】with strong suction cups on the heater guard and the thermometer, it's easy to install the aquarium heater no to the tank walls or bottom, please keep them fully...
  • 【Digital LED Display Controller】the external IC temp controller can show the water temp with 2 blue LED digits. Only show Fahrenheit degrees. To set the temp, just press the button over and over...
  • 【Quartz Tube & Plastic Guard】With high-quality quartz glass tube, it's very durable and explosion-proof, this fish tank heater can be used for saltwater and freshwater aquariums, service life can...

Last update on 2022-01-20 / Affiliate links / Images from Amazon Product Advertising API

The Hydor In-Line External Heater works great if your tank is smaller and you prefer the heater to be on the outside.

This heater features Positive Thermal Coefficient technology, exclusive to the brand per the manufacturer, which ensures maximum safety to prevent overheating.

Quick Facts

Wattage options:

200W – 300W (Other watts in different models)

Safety Features:

  • High precision electronic temperature control

Warranty:

3-year warranty

What fish is it best for?

  • Freshwater fish
  • Saltwater fish
Hydor ETH 300 In-Line External Aquarium Heater, 300w, 5/8" hose
  • Suitable for marine and tropical aquariums
  • Easy to use
  • High precision electronic temperature control
  • For external use
  • 5/8 inch hose

Last update on 2022-01-20 / Affiliate links / Images from Amazon Product Advertising API

The Fluval M200 Heater is a great option for smaller tanks.

It is a simple, easy-to-use heater with fewer bells and whistles than many heaters on the market. However, the reliability is excellent.

Quick Facts

Wattage options:

50W – 200W

Safety Features:

  • Temperature dial
  • Indicator light for active heat mode

Warranty:

5-year warranty

What fish is it best for?

  • Freshwater fish
  • Saltwater fish

Pros

Cons

  • Temperature dial is easy to read
  • Simple installation
  • Takes up small amount of space
  • No indicator light for standby mode
  • No heater guard
  • No overheat or dry sensor
Sale
Fluval M200 Submersible Heater, 200-Watt Heater for Aquariums up to 65 Gal., A784
  • Aquarium heater that blends into the aquarium environment with built-in reflective technology that mirrors the surrounding colors
  • Computer-calibrated thermostat and easy-to-adjust temperature control dial
  • Shock resistant Borosilicate glass and high density ceramic heat sickness
  • Easy to install with slim profile tube for easy placement

Last update on 2022-01-20 / Affiliate links / Images from Amazon Product Advertising API

The EHEIM Jager Aquarium Thermostat Heater is a fully submersible heater.

It has an automatic shutoff if the water level gets to a dangerous level and a TruTemp dial that recalibrates the heater for top accuracy in regulating water temperature.

Quick Facts

Wattage options:

25W – 300W

Safety Features:

  • TruTemp Dial – adjusts temperature precisely from 65 -93 degrees Fahrenheit, with control accuracy of +/- 0.5 degrees
  • On/Off Indicator Light
  • Thermo Safety Control – shuts off the heater when it is removed from the water

Warranty:

3-year warranty

What fish is it best for?

  • Freshwater fish
  • Saltwater fish
  • Terrariums

Pros

Cons

  • Accurate and steady water temperature
  • Quick and responsive customer service reported per our research
  • The units tend to be long in length – be sure to get the specific specifications of the size you want to purchase and measure your tank to ensure it will fit
Sale
Eheim 3619090 Jager Aquarium Thermostat Heater 300W
  • Heater is meant for Tanks between 159-264 Gallons.
  • Size of Heater is 20” X 1.4” Diameter
  • Fully submersible, will automatically turn off when water level dips too low.
  • Thermo safey control protects against running dry.
  • Made of shock resistant and shatter proof glass for fresh or marine water.

Last update on 2022-01-20 / Affiliate links / Images from Amazon Product Advertising API

More Aquarium Heater FAQs

How Many Aquarium Heaters do I Need

Whether or not you need two heaters in your aquarium depends on the size, as well as the temperature of the room location where you put it.

If your fish tank requires 200+ watts of heat, purchasing two 100W heaters is better than using one 200W heater.

If a heating element were to malfunction in one, the second heater acts as a backup to prevent the water temperature from falling to a dangerously low level.

On the other hand, if one of the heaters were to overheat, with such a large volume of water it is not likely to be powerful enough to overheat the entire aquarium.

How Do I Make Sure My Heater is Working Correctly

The quickest and surefire way to know if your heater is working properly is by using a thermometer to gauge the water temperature.

Typically, it should be between 76 and 80 degrees Fahrenheit for tropical fish, or 68-72 degrees Fahrenheit for goldfish.

A good way to test this is to place the tip of the thermometer into water that you know is at a lower temperature, then feel along its shaft until it reaches room temperature.

The difference in reading will tell you how close your aquarium’s water temperature is getting to either extreme range before needing adjustment.

How Often do I Need to Check My Aquarium Heater

You should check your aquarium heater and the water temperature every day or two, to make sure they are still running at optimal efficiency.

If you choose an in-line heater that is easy to access, it will be easier for you to monitor its performance than if you have one built into a wall of your tank.

Recap Comparison Chart

Final Words

The Fluval E200 is the top pick from the reviews included in this report.

The specifications are good, the overall reviews are good from the aquarist communities in reference to ease in setup, installation, and calibration.

If the size of this Fluval does not fit your aquarium needs, check out the other options by Fluval to see if they have one well-suited for you.

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