The Best Aquarium Heaters (Selecting the Best & Designing A Heating System 2021 Reviews 🏅)

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Aquarium heaters are one of the more essential, yet more fail prone piece of equipment that you can add to your aquarium. The vast majority of us in the aquarium keeping hobby keep fish that require tropical temperatures so a heater is a must.

There are many heaters out on the market and it is very easy to just select a cheap aquarium heater and think you are good to go. The best aquarium heaters are not fail prone, built very well, and will heat your aquarium safety. I will go over what is a submersible aquarium heater and also talk about glass vs titanium heaters. I will also talk about fail safes and how to prevent a tank disaster if a aquarium heater fails (and also what usually fails). Let’s get started!

Contents show

Benefits of an Aquarium Heater

Because most of us in the fish keeping hobby keep tropical or saltwater fish, they require temperatures to be consistently around 75 – 80 degrees Fahrenheit (or 24 to 27 Celsius. Since we keep aquariums indoors in our home, most people would think that the ambient temperature of our home could keep our aquariums at a safe temperature. However, seasons change and there are certain times like in the winter where temperatures in your home can drop below 70 degrees or less in your home putting our precious livestock at risk.

The best aquarium heaters not only keep your temperature up, but are easily adjustable so you can set the temperature to what you need it to be. They are also accurate to boot. Some will even come equipped with a separate temperature controller so you add redundancy in the event a heater fails.

The Aquarium Heaters Candidates – a Quick Comparison

There are many heaters out on the Market. The list below were handpicked by our years of experience in the hobby and through various client builds. They all have their strengths in particular setups which I will explain below. This post will focus on submersible aquarium heater types.

In a hurry? I would recommend the Eheim Jager Aquarium Heater or Cobalt Neo Therm Heater

Editor’s Choice
Cobalt Aquatics Neo-Therm Heaters
Cobalt Aquatics Neo-Therm Heaters
  • Reef Tanks
  • Compact Design
  • All In One Tanks
  • Fully Submersible
Click For Best PriceBuy On Amazon
Best Value
Eheim Jager Aquarium Thermostat Heater
Eheim Jager Aquarium Thermostat Heater
  • All Setups
  • German Made
  • Lab Grade Glass.
  • Fully Submersible
Click For Best PriceBuy On Amazon
Aqueon Pro Adjustable Heater Aqueon Pro Adjustable Heater
  • All Setups
  • Lifetime Warranty
  • Fully Submersible
Buy On ChewyBuy On Amazon
Fluval M50 Fluval M50
  • 3 Year Warranty
  • Fully Submersible
Buy On Amazon
Cobalt Aquatics Accu-Therm Submersible Heaters Cobalt Aquatics Accu-Therm Submersible Heaters
  • All setups
  • Fully Submersible
Buy On Amazon
Finnex Deluxe Titanium Tube Heater Finnex Deluxe Titanium Tube Heater
  • Large Freshwater & Saltwater Tanks
  • Fully Submersible
Buy On Amazon
Finnex Digital Touch Control Titanium Heater Finnex Digital Touch Control Titanium Heater
  • All setups
  • Fully Submersible
Buy On Amazon
Hydor In-Line External Heaters Hydor In-Line External Heaters
  • Canister Filter Setups
Click For Best PriceBuy On Amazon
Hygger Titanium Tube Submersible Heater with Controller Hygger Titanium Tube Submersible Heater with Controller
  • Controller
  • Budget Friendly
  • Fully Submersible
Buy On Amazon

The Best Aquarium Heaters – 9 Best For 2021

Let’s go into the details and see why each heater made the cut

1. Cobalt Aquatic Neo-Therm Heaters – The Most Accurate Heaters on the Market

Editor's Choice
Cobalt Aquatics Neo-Therm Heater

Editor's Choice

Compact and accurate. This is the the best aquarium heater you can buy today

Click For Best Price Buy On Amazon

If you have a system that requires precise constant water temperature with sensitive inverts, corals, or fish like a reef tank, the Cobalt Aquatics Neo-Therm Heaters can’t be beat. Cobalt Aquaitcs computer tested all their Neo therm heaters. They are accurate up to 0.5 degrees Fahrenheit (better than most controllers on the market in fact), the Neo therm heater to many in the reef aquarium hobby is the go to. The Neo-Therm is also one of the most compact heaters. It can fit in any all in one aquarium and will hide well if placed inside a display tank. For overall features, this is the best submersible aquarium heater you can buy today.

It does come with a higher price tag though. The Neo Therm heater is one of the more expensive heaters available and they also only come in smaller wattage sizes, meaning you will need multiple units to run a larger tank.


  • Accurate up to 0.5 degrees Fahrenheit!
  • Manual water temperature adjustment dial
  • Compact design – fits in all in one systems


  • Only available in smaller wattage
  • Expensive

2. Eheim Jager Aquarium Thermostat Heater – Old Faithful with Legendary Brand Name 

Best Value
Eheim Jager Aquarium Heater

Best Value

Very accurate, durable, and German made. A great value buy for any aquarium

Click For Best Price Buy On Amazon

Ah the Eheim Jager Heaters. They have been around seemingly forever and completely unchanged for ages, and there is a good reason why. It is simply a very well built and reliable heater. Quality German made, UL listed electronics, and a manual adjustable heater gauge are it’s main features. It is accurate up to 0.5 degree Fahrenheit of the desired temperature you set. This makes it as accurate as the Cobalt Neo-Therms. It also has the ability to be re-calibrated!

Because it is it a quality manufactured heater, it simply hasn’t been updated in years and looks the part. It is big and bulky, it uses old school lab grade glass, and the adjustable dial itself is cumbersome. However, Eheim’s legendary name brand is behind it and anyone who has been in the aquarium industry knows the great quality and durability that Eheim manufactured products bring. It’s ugly looking and big, but you won’t be disappointed using this as your aquarium heater.


  • German made and Eheim name
  • Accurate up to 0.5 degrees Fahrenheit
  • Can be re-calibrated


  • Big and bulky
  • Old school lab grade glass design
  • Temperature dial is a bit clunky

3. Aqueon Pro Adjustable Heater – An Aquarium Heater with Limited Lifetime Warranty 

Aqueon Pro Adjustable Heater

The only heater on the list that offers a lifetime warranty

Buy On Chewy Buy On Amazon

A shatterproof adjustable submersible heater with a limited lifetime warranty. That sounds like a great heater and rightly so on this list. Aqueon has been in the Aquarium industry for a long time and many of us have trusted them for our tanks as many of the standard tanks old these days are manufactured either by Aqueon or Marineland.

The Aqueon Pro Adjustable Aquarium Heater comes with a water temperature dial that is painless to adjust to your desired temperature. Because it’s a manual control, it is less prone for its temperature configuration to fail because the setting will not reset during a power outage. The Aqueon Pro is accurate within 1 degree, which is adequate for most setups, but would be considered suspect in a delicate environment such as a reef tank.


  • Lifetime warranty and Aqueon Name
  • Manual water temperature dial that will not reset in a power outage
  • Shatterproof design


  • Only accurate up to 1 degree
  • No separate controller for redundancy

4. Fluval M-Series Heater – A Reliable Aquarium Heater

Fluval M-Series Aquarium Heater

Made of Borosilicate glass and backed by a 3-year warranty. The Fluval M-Series is a good value buy that balances performance and cost

Buy On Amazon

The M-Series is Fluval’s value heater offering, and one of the common ones you will see at pet stores and local fish stores. If all the heaters you will find at non-specialized pet stores, this will likely be the best heater you will find on the rack. It’s made of Bososilicate glass and backed by a 3-year warranty. Fluval has a big prescence in our aquarium industry and many of their products are known for their reliability.

While heaters are prone to failure, this is still one of the better ones out there. With proper backup protocals, you should be happy with purchasing an M-Series.


  • Good price
  • Hagen/Fluval name
  • Computer calibrated
  • More compact than the Eheim


  • Inferior to the Eheim heater
  • Still prone to break from large fish
  • No separate controller for redundancy

5. Cobalt Aquatic Accu-Therm Heaters – Computer Tested Accurate Aquarium Heater

Cobalt Aquatics Accu Therm

A budget heater from Cobalt Aquatics. Computer tested and constructed of Borosilicate glass

Buy On Amazon

The Cobalt Aquatics Accu-Therm Submersible Heater may not be the prettiest heater on this list, but they offer a computer tested heater for added assurance that the heater will heat to the desired temperature. It is also equipped with an easy to use manual water temperature adjustment dial that is will not reset during a power outage. It is constructed of Borosilicate glass, which is more resistance to thermal shock (e.g. – your submersible heater exploding). This glass is what is typically used in lab environments, making this a higher end constructed heater than your typical budget glass heater.


  • Computer tested
  • Lab grade borosilicate glass construction
  • Manual water temperature adjustment dial


  • Ugly looking design
  • Accurate up to 2 degrees – A separate controller is must!

6. Finnex Deluxe Titanium Heaters – The Heater of Choice for Monster Fish Keepers

Finnex Digital Heater

Titanium Heater with a Digital controller. Excellent for larger tanks

Buy On Amazon

For those of us with large tanks over 200 gallons, it is difficult to not only find a high wattage heater, but also a heater that is about to take the punishment of large aggressive fish who may trash about in the aquarium and knock down rocks and equipment.

This is where the Finnex Deluxe Titanium Heaters answer the call. It is a titanium built heater, which make them virtually indestructible. A titanium heating element more corrosive resistant then glass heaters, making it ideal for saltwater environments.

It unfortunately does not have a built in way of controlling water temperature, which is why this package comes with its own controller. However, because there is no adjustment dial on the heater itself, there is no redundancy on the submersible heater unit to protect against failure. The controller itself is only accurate up to 2 degrees Farenheit, which is fine for freshwater and fish only saltwater setups. Reef tank users will want to consider purchasing the Finnex Titanium Heater Rod only and go with a more accurate aquarium heater controller or utilize a high end controller like an Apex Controller.


  • Titanium built design
  • Comes with a digital controller
  • Available in up to 800W


  • No adjustment dial on submersible heater itself
  • Controller is accurate only up to 2 degrees Fahrenheit
  • Not available in smaller sizes

7. Finnex Titanium Heaters – Titanium Heaters for the Rest of Us

Finnex Titanium Heaters

A budget version of the Deluxe Finnex heater. This is a titanium heater for the masses!

Buy On Amazon Click For Best Price

Titanium heaters are considered better than glass heaters due to the fact that titanium is more corrosive resistant and are nearly indestructible. Our last heater was only available in high wattage, but this variation of Finnex Titanium Heaters are for the rest of us. With very similar pros and cons, this heater will get you a titanium submersible heater had a reasonable price. Like with most titanium heaters, the heating element does not have a manual adjuster on board. To program to the desired temperature, you have to use the controller that comes with it.


  • Titanium built design
  • Comes with a digital controller


  • No adjustment dial on submersible heater itself
  • Controller is accurate only up to 2 degrees Fahrenheit

8. Hydor In-line Heaters – A Great Choice For Canister Filter Users

Hydor In-Line External Heaters

This In-Line heater is an excellent choice to pair with a canister filter. Keeps your heater out of your display tank!

Click For Best Price Buy On Amazon

The Hydor Inline Heaters are the perfect choice for aquarists who own a Canister filter. Because this heater runs through your return line, you do not have to worry about this heater being inside of your tank and prone to the abuse some of your fish would cause on it moving rock work or even yourself hitting it accidentally while performing maintenance.  It is constructed with Hydor’s patented PTC heating technology. The way the unit works is that it is made of a special polymer that has been printed with aquarium safe ink. This ink heats up the passing current as the water is transferred into your aquarium. It really is a fascinating technology!

It does come with some major drawback though. It must be installed in the vertical position, which can be a problem for those with limited space in their cabinets. It can be only installed with vinyl tubing, making it non-ideal for setups with hard plumbing. Hydor also does not state how accurate the heater is on their specs, which forces me to say a controller is a must. It is a great alternative to a submersible aquarium heater.


  • External heater
  • Slick operation and patented technology
  • No risk of heater burn on fish


  • No specs from Hydor on how accurate it is
  • Can only be used with vinyl tubing
  • Only available up to 300W

9. Hyggar Titanium Aquarium Heaters – New Player on the Market Delivering Budget Titanium Heaters

Hygger Saltwater Titanium Heaters

An affordable way to get a titanium heater and heater controller in one package

Buy On Amazon

This aquarium heater really surprised us. The Hyggar Titanium Heaters come with a digital controller that claims 0.5 degrees of accuracy. That claim would make it one of the most accurate controller on the market.

They are a unknown brand at this point, but the reviews have been pretty stellar, enough for us to consider them on our list for aquarists looking for an all in one solution titanium heater with a controller.


  • Titanium design
  • Controller claimed accuracy of 0.5 degrees


  • New manufacturer

How to Choose the Right Aquarium Heater

I’ve provided a lot of choices here and it can be frustrating to figure out which one works best. No worries though, let me help you out.

Size of Aquarium Heater

All the aquarium heaters listed on this blog post come in various sizes. Some like the Eheim Jager are very bulky while the Cobalt Neo Therm Heaters are very compact in size. If you do not have a sump or canister filter, the size of the heater will come into play as it may stick out like a sore thumb. Smaller heaters are easier to hide and also getting multiple heaters will help with hiding them in the tank (redundancy is also another reason to get more than one heater which I’ll explain in further detail).

Types of Aquariums

The type of aquarium you own will help determine what heater you will need. For example, if you have a fish only freshwater community tank with most hardy fish, you can likely get by with a single heater and a relatively cheap one.

If you have larger predator fish like Cichlids or Arowanas, you will want a submersible heater that can take a beating. This is where Titanium heaters can come into play as they are virtually indestructible.

For those of us who have sensitive inverts or exotic fish like you may have with a saltwater reef aquarium, accurate and reliable temperature is critical. A swing in temperature could cost us thousands of dollars in lost livestock with such setups. Therefore, as a reef tank owner, it is imperative that we build our heating system with multiple redundancies and safeguards to protect our livestock.

Types of Aquarium Heaters

I did throw out a number of terms when it came to fish tank heater construction so I can be a little more detailed here. A submersible aquarium heater will typically be constructed with the following materials:

  • Glass
  • High Quality Glass like Quartz or Bososilicate
  • Titanium

Glass heaters are what you will typically find with value based brands that are not listed on this list. I have completely ignored these because they are prone to exploding in a tank and shattering! Not something you want:

Exploded Heater

Highly quality glass like what you see with the Ehiem and Cobalt Accu Therm heaters are durable glass that is resistant to thermal shock and less prone to exploding like above. They can still crack if dropped or hit by a rock, but it normal operation they should be fine, especially if they are placed in a safe area like a sump.

Titanium heaters like the Finnex heaters are virtually indestructible and great for tanks with larger fish. They also tend to be the most expensive of the lot.

Your Budget for an Aquarium Heater

I have listed a number of quality heaters in this post in all ranges of budgets. Once thing to note is that many aquariums will run multiple heaters and I am aware that not everyone will have the budget to deploy a multiple heater setup. The heater for bang for the buck I feel is the Aquaeon Pro Adjustable Heaters. The Aqueon pro offers the best mix of quality and price.

Where to Place Your Aquarium Heater

It is best place your fish tank heater in an area that gets a good amount of flow. This will normally be an area in close proximity to a power head, power filter, or air stone. You also want to keep aesthetics in mind so if you are placing the heater directly into your display, you will want to place the heater behind rock work or plants.

Placement is even easier with an all in one aquarium as there are compartments available in the return section where you can place your submersible aquarium heater in. If you have a sump, it’s even easier can you can place them in your sump after your first chamber.

How Many Watts Does My Aquarium Heater Need to Be?

It is actually a very simple rule of thumb that unfortunately gets confusing if you visit aquarium forums. The rule is 3 watts per gallon of water. The chart below provides a clear breakdown on the common aquarium sizes for reference

Tank SizeWatts Needed
10 G30 Watts
20G60 Watts
29G87 Watts
40G120 Watts
55G165 Watts
75G225 Watts
90G270 Watts
125G375 Watts
180G540 Watts
225G675 Watts
300G900 Watts

What is the Best Aquarium Heater? (Our Recommendation)

So we have discussed quite a lot at this point. It’s time to bring in the verdict. The answer may surprise you.

As we mentioned, the best bang for the buck for those who are only able to purchase a single heater would be the Aquaeon Pro Adjustable Heaters. For those of you not on a tight budget though, let’s talk about the best setup — which is setting up an aquarium heater system.

An Aquarium Heater System – The Expert’s Approach

Aquarium heaters unfortunately are prone to a number of failures. These failure points are:

  • The aquarium heater explodes
  • The aquarium heater cracks
  • The aquarium heater’s internal thermometer fails
  • The aquarium heater’s off/on mechanism fails
  • The aquarium heater’s settings reset after a power outage

That is A LOT of failure points. It’s also a bit scary to know that the #1 tank crash reason are aquarium heater failures. It’s not disease, it’s not a power outage, but your heater failing. That’s correct, a measly $30 heater can be the cause of you losing hundreds of dollars of fish and pets that you have owned and cherished for many years.

This is why we recommend purchasing an aquarium heater system. This would encompass:

  • The best aquarium heater from this list
  • Running two heaters instead of one that get to to the recommended wattage level
  • A separate aquarium controller that is accurate at least to 1 degree Fahrenheit and can run both heating and cooling equipment
  • A reasonable piece of cooling equipment that won’t break the bank

Eheim Jager and Cobalt Aquatics Neo Therm – My Recommended best aquarium heater

When it comes to selecting a quality aquarium heater, I feel that the Eheim Jager and Cobalt Aquatics Neo Therm are the two best heaters to select from the lot. The reasoning is:

  • Both the Eheim and Cobalt Neothem are accurate up to 0.5 degrees Fahrenheit
  • The Cobalt works great in smaller systems, where an Eheim would be considered too bulky to work
  • Both have manual adjustable dials that will not reset during a power outage
  • For larger aquariums with larger fish, I am assuming that the aquarist has a sump or background that allows one to safety store a heater keeping it away from accidents

Both these heaters met my strict criteria and receive my full recommendation.

Aquarium Heater Failsafe #1 – Running Two Heaters Instead of One

Why would we run two heaters? Well, as I mentioned, heaters have many fail points and one of them is the off mechanism failing. This will mean that the heater will stay on and effectively cook your tank. This is the #1 reason for a heater fail. When you purchase two smaller heaters, if one fails at the on position it is not powerful enough to cook your tank inhabitants. It will stay on and you should have ample warning to notice the failure and act accordingly.

Aquarium Heater Failsafe #2 – Running a Separate Aquarium Controller

Since running two heaters will give you time to act in the event one fails at the on position, you could be out of town or not present for some time to act. This is where a separate aquarium controller comes in. A separate aquarium controller has it’s own temperature probe and mechanics separate from an aquarium heater. This provides you with an additional fail safe. Now both heaters AND the controller would need to fail at the same time in order for your tank to experience a crash. That is very unlikely to happen.

The Best Aquarium Heater Controllers

So now let’s talk about aquarium heater controllers. The controllers from Finnex and Hyggar are pretty good, but the Finnex controller is only accurate up to 2 degrees and the Hyggar controllers are new to the market. There are two heater controllers that have been around for a while and trusted in other industries aside from the Aquatic industry – namely refrigeration, aquaponics, and beer brewing.

The Inkbird Aquarium Heater Controller – The Best Bang for Buck Controller on the Market

Protects Against Heater Failure!
Inkbird Heater Controller

Protect your investment with this heater controller. An excellent choice for small tanks. WiFi models now available!

Buy On Amazon Click For Best Price

I know there will be some folks on the comment section may post and say that I should talk about aquarium controllers, but to me that is a completely separate subject. Aquarium controllers are very expensive and even an entry level controller is going to cost over $200, which is going to be out of the range of many readers of this post.

The inbird is a great budget controller. The Inkbird ITC-308 is a great aquarium heater controller that is accurate up to 1 degree Farenheit. It is easy to program and has the ability to not only control heaters, but cooling equipment as well. This actually provides a TRIPLE FAIL SAFE as the cooling function will kick off in the event the aquarium gets too warm. If the aquarium gets too hot or cold, the Inkbird can sound an alarm letting you know something is wrong. There is also a wi-fi version available so you can get temperature alerts on your phone if the tank gets too warn or too cold!

Aqua Logic Aquarium Temperature Controller – A Premium Aquarium Temperature Controller

Aqua Logic Aquarium Temperature Controller

The Aqua Logic Temperature controller is the best tool available today to prevent your tank against heater failure

Click For Best Price

The Aqua Logic Aquarium Temperature Controller is a step up from the Inkbird. It doesn’t have the fancy features as the WiFi version of the inkbird, but it is more accurate and better built. It’s technology comes from the HVAC industry and has a rated accuracy up to 0.5 degrees Fahrenheit.

This controller provides even better assurance that your temperatures stay stable. I typically go with an inkbird on smaller budget builds, but if I have more budget and my client isn’t looking to get a controller, this is a definite consideration for me. If you are looking for a compete solution, I would recommend looking into my best aquarium controller post for details about controllers that are able to automation multiple aquarium functions.

The Best Aquarium Cooling Fan – The Final Fail Safe

Aquarium Cooling Fan

Aquarium cooling fans are cheap and effective ways of pushing heat away from the aquarium

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Since these aquarium heater controllers have the ability to cool down a tank, let’s get a reasonable piece of cooling equipment. An aquarium chiller is going to be out of the budget range of many aquarists so a cooling fan is a good option for us to look into.

The IPETTITE Aquarium Cooling Fan is a very reasonable piece of an equipment when teamed with an aquarium heater controller can provide some cooling the event your tank gets too warm. It’s not a chiller, but it should get you by for most situations. If you need to take it to another level, you can try looking at my best aquarium chiller post for options regarding chillers.

Wrapping It All Up On Best Aquarium Heaters

Well, this was a pretty long post. I hope I was able to provide you with the information you need to make the best informed purchase. As I stated earlier, there is a reason for these aquarium heaters to be on our best of lists as they all have their place depending on your aquarium situation and budget.

If you have any questions, please leave a comment in the comment section. Thanks for reading :).

by Mark

Mark is the founder of Aquarium Store Depot. He started in the aquarium hobby at the age of 11 and along the way worked at local fish stores. He has kept freshwater tanks, ponds, and reef tanks for over 25 years. His site was created to share his knowledge and unique teaching style on a larger scale. He has worked on making aquarium and pond keeping approachable. Mark has been featured in two books about aquarium keeping - both best sellers on Amazon. Each year, he continues to help his readers and clients with knowledge, professional builds, and troubleshooting.


  1. Hi Dave,

    I would go with 2 150W heaters to be safe. It’s okay to oversize your wattage total given your situation and the face that you will be running two heaters.

  2. 65 gallon Salt water tank for Fish only with Live Rock. I want 2 heaters. In the winter, I allow the house to drop as low as 62 degrees. Do I need more than a total of 65×3=195 watts (I assume that with 2 heaters, I would need 2 100 watt devices)


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