Best Aquarium Heater Reviews – Top 7 Ratings, Guide, FAQs & More

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You’ll agree with us when we say that going out and buying an appropriate heater for your aquarium can be a very intimidating experience. 

Keeping this in mind, we’re bringing you our top picks for the best aquarium heaters out there and information about what specific purposes they are suited for. 

In today’s post, we’ll be helping you figure out how to judge whether a heater is suitable for your fish or not and discussing the factors you need to look out for when getting one. 

Top Pick

If you’re looking for a durable heater that’s easy to use and set up, this is the product for you. It has a sleek design that goes well with all types of household aquariums.

Runner Up

This heater can heat up a fish tank much quicker than its competitors. You’ll want to get this if you live in a region where the temperature changes very erratically.

Also Great

The built-in thermostat in this heater makes for a consistent temperature in your aquarium. Its indicator light makes it easy to monitor when the heater is on.

We’ve spent months testing out aquarium heaters of all shapes and sizes and in the end, we’ve concluded that these three are the best ones you can find anywhere. 

Now, let’s get into the reviews for our top 7 picks for the best aquarium heaters.

Best Aquarium Heater - Top 7 Reviews

1. All-Around Best Aquarium Heater - Aqueon Pro Submersible Aquarium Heater Review

You can feel the premium build quality of the Aqueon Pro Submersible Aquarium Heater as soon as you hold it in your hand. It claims to be “nearly indestructible” and we’re inclined to believe them as the product feels very sturdy. 

It comes with a built-in thermostat that helps the heater keep the water temperature consistent. It also has an LED light that is constantly on and tells you the state of the heater currently; Red light means it’s heating, green light means it’s not heating.

Features of Aqueon Pro Submersible Aquarium Heater – Best Aquarium Heater

  1. Adjustable temperature from between 68 to 88 degrees Fahrenheit (20 to 31 degrees Celsius)
  2. Shatter-proof
  3. Auto-shut off feature
  4. Built-in LED light
  5. 150 Watt Operating Capacity
  • Water temperature remains constant
  • Highly durable
  • LED light makes for easy monitoring
  • Lifetime warranty
  • Capable of heating tanks up to 50 gallons
  • Dial slightly difficult to use when submerged

If you’re looking for a long-lasting, durable aquarium heater that is both effective and easy to use, we highly recommend this product. It has a compact design that doesn’t call attention to itself.

2. Best Fast-Heating Aquarium Heater - ISTA External Aquarium Heater Review

This is an in-line heater that is connected between your filter and your aquarium. It comes with two temperature sensors, one that measures inlet water temperature and one that measures outlet temperature. 

It comes in five different sizes with the largest one working at 500 Watts which is enough operating capacity to effectively heat an aquarium as big as 150 gallons. 

We were impressed by its small, compact design which does not take up space inside the fish tank. It has a digital read-out that stands out with its bright, red display and is easy to read.

Features of ISTA External Aquarium Heater

  1. Sizes ranging from 150 to 500 Watts
  2. Two built-in temperature sensors
  3. ⅝ inch water hose
  4. Temperature displayed in Celsius
  5. Weight: 15.8 ounces
  • Relatively inexpensive
  • Heats up water very quickly
  • Easy to install
  • Easy to monitor
  • Clog-proof
  • Sturdy
  • Has to be mounted in a very specific vertical position

This is a very powerful aquarium heater that you can get to fulfill even the biggest of your aquarium needs. Even though it’s very powerful, it’s not too big and doesn’t take up too much space.

3. Best Budget Aquarium Heater - Tetra HT Submersible Aquarium Heater Review

This heater comes in two sizes: 50 Watts and 100 Watts. 

The 50 Watts variation is sold for as low as $15. Being able to buy an aquarium heater that’s able to heat a fish tank up for only $15 is something we’d only dreamt of in the past. This is an amazing deal that you shouldn’t pass up on if you have an aquarium this size. 

It is fully submersible and it can be placed in a number of positions horizontally or vertically inside your fish tank. It’s extremely small in size which means you can easily conceal it with aquarium ornaments or plants. 

Features of Tetra HT Submersible Aquarium Heater 

  1. Comes in two sizes: 50 and 100 Watts
  2. Weight: 7.2 ounces and 8.8 ounces respectively
  3. Built-in electronic thermostat
  4. Auto-shut off feature
  5. Indicator light
  • Extremely cheap
  • Small in size
  • Lightweight
  • Highly Durable
  • Shuts off automatically to prevent overheating
  • Temperature not adjustable. Can only be set at 78 degrees Fahrenheit (25 degrees Celsius)

If you don’t have a lot to spend when it comes to an aquarium heater, this product is ideal for you. It’s priced cheaply but it’s effectiveness and quality is as excellent as ever.

4. Best Safe Aquarium Heater - Cobalt Aquatics Flat Neo-Therm Heater Review

This product was a breath of fresh air due to its extremely flat design. It’s only ⅓ inches thick that can easily stick inside your aquarium and be concealed. 

It has an auto-shut off feature that prevents overheating and allows it to keep the tank at a consistent temperature. 

The side-dial that is located near its top coupled with its lights makes it easy to monitor and adjust accordingly. The dial has ridges that are easy to grip when the aquarium heater is submerged under water.

Features of Cobalt Aquatics Flat Neo-Therm Heater

  1. Sizes ranging from 25 Watts to 300 Watts
  2. Made from resin/thermoplastic
  3. Auto-shut off feature
  4. Weight: 14.4 ounces
  5. Adjustable temperature setting between 66 to 96 degrees Fahrenheit (18 to 35 degrees Celsius)
  • Can heat aquariums up to 100 gallons
  • Highly durable
  • Prevents overheating
  • Extremely small in size
  • Adjustable temperature for enhanced control
  • Doesn’t have a digital temperature reading 
  • Suctions cups may not be strong enough

If you’re looking for a very tiny aquarium heater that doesn’t call attention to itself, this is ideal for you. It’s made from extremely strong plastic and has easily adjustable temperature controls.

5. Best Aquarium Glass Heater - ViaAqua Quartz Glass Submersible Heater Review

We were skeptical when testing this aquarium heater out as it’s made of Glass. We’ve had bad experiences with glass heaters in the past with them shattering or cracking but we’re pleased to tell you that we’ve been using this heater for many months and it has shown not even the smallest signs of cracking or any sort of deterioration. 

It has a highly visible temperature setting that is easily readable even when the heater is fully submerged.

It has a red indicator light that shows it’s heating appropriately and it makes a clicking noise when the heater turns off automatically when the adjusted temperature is reached.

Features of ViaAqua Quartz Glass Submersible Heater

  1. Weight: 10.9 ounces
  2. Made from shatter-resistant Quartz Glass
  3. Suitable for both saltwater and freshwater aquariums
  4. Operating capacity from 50 to 300 Watts
  5. Comes with suction cups for mounting security
  • Indicator light for easy monitoring
  • Very sturdy
  • Inexpensive
  • Overheating safety mechanism
  • Low energy consumption
  • Temperature reading sometimes inaccurate

If you want a great-looking glass heater for your aquarium, this is the product you’re looking for. Its glossy finish coupled with its compact design makes it a great addition to your fish tank.

6. Best Automatic Aquarium Heater - Eheim Jager Aquarium Thermostat Heater Review

The Eheim Jager Aquarium Thermostat Heater is a European product. It comes in eight different sizes ranging from 25 Watts to 300 Watts.

It has a Thermo safety control to prevent against running dry and its patented TruTemp dial made it extremely easy for us to recalibrate the aquarium heater for accurate temperature control. 

It’s made from shock-resistant and shatter-proof material that works great in both freshwater and marine environments. 

We mounted it horizontally in our aquarium and it’s been working for months without a single hiccup.

Features of Eheim Jager Aquarium Thermostat Heater

  1. Fully submersible
  2. Adjustable temperature (18 to 34 degrees Celsius)
  3. Built-in indicator light
  4. TruTemp dial with readjustment ring
  5. Thermo-safety control for “running-dry” protection
  • Large heating surface area
  • Automatically turns off when taken out of water
  • Three-year warranty
  • Bright indicator light makes for easy monitoring
  • Easy to set up
  • Long, large body which may be difficult to hide

If you are forgetful and are worried you might leave your heater on at some point when you take it out of your aquarium, this is the aquarium heater you should go for. Its safety features make it a very reliable and self-sufficient piece of equipment.

7. Best External Aquarium Heater - Hydor In-Line External Heater Review

This in-line heater heats the cleaned water that comes out of your filtration system into your aquarium. 

It came with clear instructions and was very easy to assemble. Since it has to be set up externally and you don’t have to get your hands wet, setting it up took no time at all. 

The heating element is self-limiting which helps prevent any risks of overheating. 

Features of Hydor In-Line External Heater

  1. Three variations: 200 Watts with ½ inch hose, 200 Watts with ⅝ inch hose, 300 Watts with ⅝ inch hose
  2. Built-in indicator light
  3. Self-limiting heating element
  4. Suitable for both fresh and marine environments
  5. Shatter-proof and shock-resistant body
  • Lightweight
  • Small in size
  • Sturdy
  • Works for aquariums as big as 100 gallons
  • Can be placed in aquariums as small as 2.5 gallons
  • Prevents overheating
  • Built-in thermometer does not work accurately enough in small tanks
  • Temperature control knob is a bit too sensitive

If you don’t want extra clutter inside your aquarium and just want a heater that will be able to heat your tank from the outside, you’ve just found your product. Its small, elegant design and easy to use controls make it a great choice for the minimalist fish-keeper.

best aquarium heater

Buyers’ Guide

What are the different types of aquarium heaters? 

There are several different types of aquarium heaters available in the market that can be suited to different needs and home environments. Thus, it is important that you familiarize yourself with at least the most popular types so you are able to make an informed decision when buying an aquarium heater. The different types of aquarium heaters are: 

  • Immersible Heater

This heater is also known as a hanging heater as it hands on the back of your aquarium. It consists of a heating element that is placed inside the water where it heats up your tank. This type of heater is cost-effective and popular among novice fish-keepers because it’s easy to use. 

  • In-line Heater

An in-line heater is attached to your filtration system. It puts itself between your fish tank filter and your aquarium and thus, it heats the cleaned water that’s coming out of your filter and going into your aquarium. This type of heater is common in larger fish tanks.

  • Submersible Heater

This type of heater can be fully submerged underneath your aquarium and thus, gives you more options in terms of placement. These types of heaters usually also have built-in thermostats and thus, are able to regulate water temperature more consistently. 

  • Substrate Heater

These types of heaters were popular in the ‘90s but are quickly becoming uncommon as they are not very effective. They are placed underneath your substrate and work by heating your substrate. This can be okay for planted tanks but it doesn’t work very well when it comes to complete tank heating.

What should I look for when buying an aquarium heater? 

There are a few important factors that you should keep in mind and observe when buying your aquarium heater. As long as you keep these factors in mind, you won’t have to worry too much about whether or not your heater is appropriate or not. These factors are: 

  • Operating Capacity 

This is, by far, the most important thing that you should look for. When buying an aquarium heater, you should make sure that it is able to work at a capacity that is able to heat your aquarium effectively. If you get one that’s too weak for your aquarium, it won’t heat it effectively or fast enough. If you get one that’s too strong, you might face overheating problems that could even be lethal for your fish in extreme cases. 

  • Adjustable Temperature 

This is an extremely handy feature to have and we highly recommend that you get a heater that has this feature. 

Some cheaper heaters don’t have this feature. They just have a set temperature. This can be quite restrictive as there might come a time when you might change your fish in the future or a change in conditions might call for a change in your water temperature which you wouldn’t be able to facilitate.

  • Accessible Controls 

This might sound like a no-brainer but you’d be surprised as to how frustrating it can be to adjust knobs that are completely submerged underwater. 

Be sure to get a heater that has big, accessible knobs and buttons that are easy to control even when submerged. 

Does my room temperature have any effect on my heater’s requirements? 

Yes, it definitely does. If you have your aquarium in a room that’s colder, you’ll want your heater to operate at a higher capacity and for longer periods of time. If you have a warmer room, you may require your heater to be on for a shorter time or you might not need it at all sometimes. 

How do I protect my fish from direct contact with the aquarium heater?

Most good-quality aquarium heaters come with solid protectors or guards that cover the heating element completely. This protects the fish and plants in your aquarium from coming into direct contact with the heater. 

If your guard gets damaged or broken or if your heater simply doesn’t have a guard to begin with, we recommend buying one from your local pet store or the internet as they are readily available. 

How big of a heater do I need for my aquarium? 

It’s very important that you get your heater’s operating capacity or “Wattage” right when buying one for your aquarium. 

As a general rule of thumb, it’s a good idea to get a heater that operates at 3-5 Watts per gallon. So, for example, if you have a 15-gallon fish tank, it’s a good idea to get a heater that works at a capacity of at least 45 Watts. 

If you’re not quite sure how strong of a heater to get, you can always just get a bigger one that has adjustable temperature controls. This is extremely important as you don’t want to overheat your fish tank. 

Frequently Asked Questions


Do all aquarium fish require an aquarium heater? 

No. As a matter of fact, some fish even require lower temperatures of water for which some fish-keepers have to get chillers for. 

Before getting an aquarium heater, research what your fish’s needs are.

Coldwater fish like Goldfish are able to survive without a heater in most climates. Whereas if you have tropical fish, they require the water temperature to be between 74 and 86 degrees Fahrenheit (23 to 30 degrees Celsius). Thus, for them, you’ll have to invest in an aquarium heater. 

You can also think about skipping an aquarium heater if you have tropical fish but live in a tropical region where the temperature does not go below 23 degrees Celsius all-year round. A lot of people do this in tropical regions but we still do not recommend it as the weather is unpredictable and there might be some days when you might need it for your aquatic pets.

Where on my aquarium should I mount my aquarium heater? 

This generally depends on the type of heater you have. In-line heaters are placed between your filter and your aquarium while substrate heaters are placed underneath your gravel. 

Submersible and Immersible heaters are usually placed on the back of your aquarium. This helps circulate the heated water evenly throughout the fish tank and also, it prevents your heater from blocking the view. 

How long should I leave my aquarium heater on? 

We highly recommend getting a heater with a built-in thermostat. These heaters are constantly plugged in and remain on. They constantly monitor water temperature and turn on and off by themselves in order to keep the temperature of the water consistent. 

If you have a heater that doesn’t have a built-in thermostat and just has a heating element, you’ll have to turn it off and on yourself. How long you keep it on will depend on a number of factors such as your room’s temperature, your heater’s wattage, your aquarium size, etc. We recommend consulting your local pet store in order to determine how long you should keep your heater on in that case.

How much power does an aquarium heater normally need? 

Aquarium heaters are usually the ones that use up the most power when it comes to aquatic equipment. Even then, they don’t really use too much power. Most companies even advertise how their aquarium heaters are specifically designed in order to keep power consumption low. 

Usually, you can judge how much power an aquarium heater will use by its wattage. Companies have the wattage of aquarium heaters listed on their box. 

Can I use a high wattage heater in a small fish tank? 

This can be done if the high wattage heater has an adjustable temperature control feature. If it has this, you can use it in a small fish tank with ease. However, we strongly discourage you from getting a high-wattage heater that isn’t adjustable. This would most definitely overheat your tank water which would be fatal for your fish. 

How do I adjust the temperature of an aquarium heater?

Check your heater’s body and read its instruction manual in order to properly determine how to adjust its temperature. Some heaters don’t even have this option but the majority of aquarium heaters do. 

This is usually done using a knob or a button on the heater that has some sort of units or temperature markings on it.

How should I monitor the temperature in my aquarium? 

Most good aquarium heaters come with built-in thermometers and thermostats that monitor the water temperature for you and make adjustments accordingly. However, we strongly recommend that you get a separate thermometer even if you have a heater that has all these features. 

You should place this back-up thermometer as far away from your heater in your aquarium as possible. It’s a good idea to monitor the temperature on this back-up thermometer regularly and make sure it matches the built-in thermometer that your automatic aquarium heater is working off of.

Final Verdict

Aquarium heaters are a piece of equipment that a lot of fish-keepers call the “final piece of the puzzle”. They play an essential role in making a comfortable living environment for your tropical fish. 

After several months of rigorous testing, we have to go with the Aqueon Pro Submersible Aquarium Heater. Its sleek, compact design makes it almost invisible inside your aquarium and you can leave it up to this piece of equipment to heat up your water quickly and keep it there using its built-in thermostat. 

And with that, we’ve come to the end of our post for the best aquarium heaters. 

Give us feedback and let us know what heater you’re using for your aquarium.

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