7 Best Aquarium Heaters In 2021

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This is our review of the best aquarium heaters of 2021

After reviewing and testing dozens of heaters, I’ve found the Fluval E Electronic Heater to be the best overall aquarium heater in 2021.

I’m a seasoned fishkeeper, with experience using most of these heaters on the list, so I combined my experience, along with the experience of others to make educated choices for the heaters on this list so that you can make the best possible decision for your aquatic friends.

The Fluval E Electronic Heater passed all of my tests from being diverse in wattages, to heating and displaying precise temperatures.

However, I do understand that your needs may be different than what the Fluval E Electronic Heater has to offer, so I reviewed other heaters that provide similar and unique benefits!

Let’s get started.

Our Best Aquarium Heaters

  1. Fluval E Electronic Heater(Best Overall Aquarium Heater)
  2. Finnex Deluxe Titanium Tube Heater(Best For Larger Tanks)
  3. Tetra HT Submersible Aquarium Heater (Best Budget Aquarium Heater)
  4. Aqueon Pro Adjustable Heater
  5. Eheim Jager Aquarium Thermostat Heater
  6. FREESEA Aquarium Heater
  7. Orlushy Submersible Aquarium Heater

Fluval E Electronic Heater

(Best Overall Aquarium Heater)

Starting out our list with the best overall aquarium heater is the Fluval E Electronic Heater.

Unlike other heaters out there, this heater comes packed with a dual temperature sensor to display both real time and ideal water temperatures so you’ll have the most detailed temperature readings possible.

The Fluval E Electronic heater comes in both a 100 watt size for smaller tanks, and 300 watt size for larger tanks.

The temperature display on this bad boy is made from a LCD panel, allowing you to see the temperature inside the tank in either Celsius or Fahrenheit.

This fully submersible heater comes with an alarm as well, which changes the color of the LED light to indicate whether the water is getting warmer than intended. 

Along with that, the heater comes with an integrated fish guard, protecting your fish from coming into contact with any heat. 

Inside the box will be a detailed setup guide, which was helpful when setting up the heater.

Fluval also hooks its customers up with a 5 year guarantee, so you won’t have to worry about this heater failing anytime soon! 

Overall, the Fluval E Electronic Heater is a solid, reliable choice for any heating needs!

  • Dual Temperature Sensor
  • Stylish Design
  • Adjustable Height 
  • Easy To See Temperature Display
  • Comes In Both 100 Watts and 300 Watts
  • 5 Year Guarantee
  • Detailed Setup Guide
  • Shows Temperatures In Both Celsius and Fahrenheit.
  • Setting up horizontally may void warranty

Finnex Deluxe Titanium Tube Heater 

(Best Aquarium Heater For Large Tanks)

Lets face it, if you’ve ever kept a 100+ gallon aquarium, finding a good and reliable heater is HARD! So, for those of you out there with larger tanks, you’ll love the Finnex Deluxe Titanium Tube Heater. 

Finnex not only made a heater powerful enough to heat an enormous sized tank, but also included necessary safety features to ensure all of your fish are healthy and happy inside.

Coming in 300, 500, and 800 watts, the power behind the Finnex Deluxe Titanium Tube Heater is no joke!

This heater features a corrosion-resistant and explosion proof tube that is virtually unbreakable! It works well in both freshwater fish tanks and saltwater fish tanks as well.

This heater comes with an external controller, making it easy for you to adjust the temperature and controls. 

So if you’re in the market for an aquarium heater for a large tank, the Finnex Deluxe Titanium Tube Heater is a great option to consider!

  • Made for larger tanks
  • Comes in 300, 500, and 800 watts
  • Comes with an external controller
  • Heater is corrosion-resistant and explosion proof 
  • Cost
  • Long Tube

Tetra HT Submersible Aquarium Heater

(Best Budget Aquarium Heater)

For those of you on a tight budget, the Tetra HT Submersible Aquarium Heater is a great choice.

It comes in both 50 and 100 watts, making it ideal for smaller tanks ranging from 2-30 gallons. 

The indicator light on this heater changes from red when heating the water, to green when the water is at the right temperature, allowing you to see what the heater is doing inside the tank.

Straight out of the box, the unit is set to heat the water to 78°F, which is ideal for most tropical fish.

Unfortunately, you cannot adjust the temperature on this heater, so that can be a bummer to some.

Otherwise, if you’re looking for a cheap yet reliable heater, the Tetra HT Submersible Aquarium Heater is a great choice.

  • Great Value For Money
  • Small and Easy To Hide
  • Easy To Install
  • Simple Green and Red Indicator Light
  • You Cant Adjust The Temperature
  • Sometimes Overheats

Aqueon Pro Adjustable Heater

Simple, reliable, and available from 50-250 watts, the Aqueon Pro Adjustable Heater is a great choice for all tank sizes.

This heater has an adjustable temperature setting, ranging from 68-88°F so that you can change the temperature of the water inside the tank to your fish’s liking.

It also comes with a constantly lit LED light, which is either red when heating the water or green when the water is at the preferred temperature.

An automatic shut-off feature is also built into the tank so that if the water gets too warm, it’ll stop and reset when the water cools down.

Above all that, Aqueon boasts a lifetime warranty on all their heaters! With that, the Aqueon Pro Adjustable Heater is a solid, reliable choice.

  • Comes In 5 Different Wattages
  • Adjustable Temperature
  • Lifetime warranty
  • High quality
  • Simple, and good looking
  • Simple red and green light system
  • Temperatures can vary by a couple degrees at times

Eheim Jager Aquarium Thermostat Heater

Like the Aqueon Pro Adjustable Heater, the Eheim Jager Aquarium Thermostat Heater comes in a range of watts(25W-300W), making it a good choice for all tank sizes.

This fully submersible heater is made from special laboratory glass, which increases its heating surface and acts as a heat shield.

You’ll be able to adjust the temperature of the water inside from anywhere between 64 to 95°F, and it also has a decently long 170cm power cable!

Only thing I don’t like about this heater is how long it is. Otherwise, the Eheim Jager Aquarium Thermostat Heater is a solid heating unit!

  • Made from special laboratory glass
  • Adjustable temperature
  • Long power cord
  • 3 Year warranty
  • Long unit

FREESEA Aquarium Heater

Small, efficient, and reliable, the FREESEA aquarium heater blows my mind with its performance.

Being one of the smallest aquarium heaters on the market, it can warm up the tank from 59°F to 94°F. I still don’t even know how FREESEA was able to do this!

With it being small, this submersible heater can be hidden pretty much anywhere inside your tank. Brownie points in my book!

It also comes packed with a nice LED display that allows you to monitor the water temperatures in real time without being too much of a distraction.

There are 3 different wattages available, those are 50 watts, 100 watts, and 300 watts. With that, this aquarium heater is able to be used in almost any fish tank setup.

Only downside to this heater is that it only comes with a 12 month guarantee, but other than that the FREESEA Aquarium Heater checks my boxes for being a great aquarium heater.

  • Great Value For Money
  • Small Size
  • Attractive Design
  • Nice LED Display
  • 3 Different Wattages
  • Insane Temperature Range
  • 12 Month Warranty
  • Heater needs to be submerged all the time to get good results.

Orlushy Submersible Aquarium Heater

Last but not least, the final aquarium heater on our list is the Orlushy Submersible Aquarium Heater.

This high quality heater is built with 2mm quartz glass to ensure that heat is efficiently distributed around the tank. It also offers adjustable temperatures ranging from 64°F to 93°F, giving you the ability to host almost any aquatic life you choose.

It comes in a variety of wattages, ranging from 100-500W, meaning this heater is available for tanks of all sizes.

It’s also a budget friendly option, being one of the cheaper choices on the list.

Overall, the Orlushy Submersible Aquarium Heater is a great choice for those looking for a reliable aquarium heater at an affordable price.

  • Affordable
  • Distributes Heat Well
  • Flexible Temperature Range
  • Comes In A Range Of Wattages
  • A Bit Large

Why Your Fish Need A Good Heater

For life inside your tank, having a top-notch heater is important.


Well, the goal of your aquarium should be to mimic the natural living conditions your fish endure in the wild. This means keeping stable water temperatures suited to your fish. The whole point of a great heater is to ensure your water temperatures don’t fluctuate.

If your aquarium heater does a poor job at regulating the temperatures inside the tank, this can cause devastating health problems for your fish(sometimes even death!).

From my experience, cheap, unstable heaters shouldn’t even be considered an option. The reason why I say this is because the first ever heater I used was a cheap bust from my local fish store, and within the first month, it had 2 failures resulting in half of my aquatic friends dying. I was devastated 🙁

Even if the heater works 95% of the time, one instance of crazy fluctuations in water temperatures can be more than enough to cause havoc inside your tank.

For that reason, it’s important to choose a great heater that is reliable and will keep your waters stable.

What To Look For When Buying An Aquarium Heater

When buying an aquarium heater, there’s a couple things you’ll need to look for. Those are: 

  • Proper Wattage
  • Reliableness 
  • Safety Features
  • Value for your dollar

Proper Wattage

One of the most important things to take into consideration when buying a heater is how much wattage your aquarium needs.

The amount of wattage your heater has is an indication of the amount of power output it produces. The more wattage it has, the more power output there will be.

When choosing the right wattage, be sure to not choose something too strong or weak for your tank.

So how many watts do you need? 

The general rule of thumb is 3-5 watts per gallon of water in your tank. So if you have a 50 gallon fish tank setup, you’ll need to buy a 150-250 watt heater.

Here’s a chart for reference:

Tank SizeWattage Needed
5 Gallons15-25 Watts
10 Gallons30-50 Watts
20 Gallons60-100 Watts
40 Gallons120-200 Watts
50 Gallons150-250 Watts
75 Gallons225-375 Watts
100 Gallons300-500 Watts


You don’t want to buy something that you’re going to have to replace in a couple months because it broke, or is not performing well. When choosing an aquarium heater, look at its reliability.

Aquarium heaters serve an important job in your tank, and if they fail to do this job, the health of your fish is at stake.

Even if the heater advertises “works 95% of the time”, the other 5% of the time, your fish are essentially done for. So please, do you and your fish a favor and purchase a reliable aquarium heater! 

Safety Features

One thing that I believe is non-negotiable in an aquarium heater is its performance and safety features. 

Whenever I was researching heaters for this article, I noticed a common trend among some fishkeeping groups, and that is the willing decision some people make to sacrifice the safety of their fish for some cheaper, feature lacking heaters.

However, that’s not me.

At the end of the day, we are parents of our aquatic friends. It’s OUR job to make sure we take the best care of these delicate pets.

When it comes to aquarium heaters, some safety features I looked for were automatic shutting off when the water gets too warm or the water levels get too low, and led lights to indicate whether the aquarium heater was on or not.

If a heater didn’t have these key features, or just didn’t perform well during testing. It didn’t make the list. Simple as that!

See, good quality heaters will last you years, so would you really want to take the risk of something going wrong because some safety features weren’t built into it over ten bucks?

Like momma said, It’s better to be safe than sorry!

Value for your dollar

Last but not least you should consider pricing when choosing an aquarium heater. Yes, I know it may sound obvious, but it’s an important thing to consider when making the final decision.

You may recall from my mini-rant, that I’m not too keen on choosing the cheapest option available, even if it means sacrificing the safety and well-being of the fish inside your tank. 

However I understand that money doesn’t grow on trees.

And THAT is why this list makes me soo happy. After reviewing and testing countless heaters, I’ve included dozens of products from different price points so that you can make the best decision for your tank and your wallet!

Also, when considering the price, it’s worth being mindful that you may need to get two heaters. I’ll cover this in the section below, but if you do fall into the category of needing two heaters, then you’ll definitely need to be mindful of the price! 

Aquarium Heater FAQ

When buying an aquarium, you may have some questions, here’s our answers to some of the most common ones.

Do I need more than one heater?

One of the most common questions I get from people wanting to buy aquarium heaters is if they should get a second heater?

From personal experience, you should only get another heater if you have a 30 gallon or larger tank.

Now I’m not against getting a second heater if you have a smaller tank, it’s just that it won’t bring that much of a benefit.

Where do I place the heater?

When setting up a heater, you should place it in the open, away from decorations.

The reason for this is because you want a heater to directly heat up the water, so giving it an open area is best!

Generally, keeping it on the wall is best. And DO NOT bury the heater in the gravel if it is not a substrate heater!

How do I make sure my heater is working properly?

Most heaters out there will have a light that will tell you if it’s powered on or not. 

For checking the temperature of the water, you can put a thermometer at the opposite end of the tank(away from the heater) to test the temperature inside the water. However, most heaters on this list already have a thermostat built into them.

Our Verdict

A great aquarium heater is one that is reliable, effective, and comes packed with a bunch of safety features.

With that, the Fluval E Electronic Heater checks all of these boxes, making it the best aquarium heater of 2021.

Photo of author
Hey there, my name is Gunnar Kennedy. I'm a fishkeeping enthusiast who's been in the hobby for over a decade now! I love sharing new ideas and helping others care for their aquatic friends!

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