10 Best Aquarium Heaters to Buy in 2019: Top Rated Models

For every pet owner, the comfort and well-being of their pet is always top priority – this is why every fish owner needs an aquarium heater. Fish are cold-blooded creatures – they cannot produce their own body heat, and need an appropriate temperature if they are to survive in an aquarium. Bets quarium heater, simply put, will help keep your fish healthy, happy, and alive, by ensuring that the water remains at a comfortable temperature for them to survive and thrive.

In addition, aquarium heaters also help ensure that the water remains at the right temperature consistently. Sudden or frequent changes in temperature can be stressful for fish, and prove detrimental for their health – this is where the best aquarium heater comes in handy.

However, when it comes to the well-being of your fish, not every aquarium heater will do. Faulty/substandard/unsuitable aquarium heaters can have all sorts of consequences, ranging from the mildly annoying to the dire and even fatal. They can shatter, provide uneven/inadequate heating, and even cause your pets’ death via electrocution or overheating/under-heating. Far from losing your money, you could end up losing your pet, and expose yourself and your family to hazards like electrocution or fires.

Purchasing the right aquarium heater can be a difficult task. Not only is there a large variety of different types of best aquarium heaters available in the market, there are also multiple factors to consider before the purchase. Taking factors like aquarium heater size and type into account is essential, and it is also important to be well-informed about tank heater placement, installation, and maintenance, so you can make the best choice possible. In this article, we are going to show you how to compare water heaters reviews list.

If you’re looking to purchase an aquarium heater, but feel overwhelmed by the vast array of choices and lack the information you need to make the right decision for your fish, our aquarium heater reviews and buying guide are all you require. We’ve scoured the market for the very best aquarium heaters that are on offer, and compiled mini reviews on each, to help you obtain a quick idea about the standout features and pros and cons of each aquarium heater. In addition, our buying guide contains everything you need to know when you set out to buy an aquarium heater. Let’s check our tank water heater reviews!

Comparison Table: Best Aquarium Heaters On the Market

To help you in the selection process, we’ve put together this handy comparison chart with which you can gain an instant idea about the main features of each of our recommended aquarium heaters. Read on if you are looking to compare water heaters reviews list:

Product Aquarium Capacity Best for (saltwater/freshwater aquariums) Type Thermostat Temp display Flexible mounting angles Warranty Wattage Rating
Aqueon Pro Heater Aquarium Heater
Aqueon Pro Heater Aquarium Heater
Up to 90 gallons Both Submersible Yes Fahrenheit Yes Limited lifetime warranty 250 Watt
4.2 of 5

Lifesmart Infrared Fireplace
EHEIM Jager Aquarium Heater
Up to 16 gallons Both Submersible Yes Fahrenheit Yes No 125 Watt
4.1 of 5

Lifesmart 8 Element Infrared Heater
Tetra HT Submersible Aquarium Heater
Between 2-10 gallons UNSPECIFIED Submersible Yes Fahrenheit Yes 2 year warranty 50 Watt
4.0 of 5

Cobalt Aquatics Neo-Therm Aquarium Heater
Cobalt Aquatics Neo-Therm Aquarium Heater
Up to 20 gallons UNSPECIFIED Submersible Yes Fahrenheit Yes 3 year warranty 50 Watt
4.0 of 5

iLIVING Infrared Heater
Hydor In-Line External Heater
Up to 80 gallons Both In-line external heater Yes Fahrenheit No – vertical only No 200 Watt
4.1 of 5

Finnex  Aquarium Titanium Aquarium Heater
Finnex Aquarium Titanium Aquarium Heater
Up to 120 gallons Both Submersible Yes Fahrenheit Yes Can be requested 500 Watt
4.0 of 5

Aquatop Aquarium Heater
Aquatop Aquarium Heater
Up to 13 gallons Both Submersible Yes Fahrenheit and Celsius Yes No 50 Watt
3.9 of 5

Penn Plax Submersible Aquarium Heater
Penn Plax Submersible Aquarium Heater
Up to 75 gallons Both Submersible Yes Fahrenheit and Celsius Yes 3 year warranty 300 Watt
3.7 of 5

Aqueon Submersible Aquarium Heater
Aqueon Submersible Aquarium Heater
Up to 55 gallons Both Submersible Yes Fahrenheit Yes Lifetime limited warranty 150 Watt
3.7 of 5

Marineland Aquarium Heater
Marineland Aquarium Heater
Up to 29 gallons Both Submersible Yes Fahrenheit Yes Available on request 100 Watt
3.6 of 5

Find The Top Rated Fish Tank Water Heater

Aquarium heaters are essential for all fish owners, as they help guarantee the health, safety and comfort of your pet by regulating the temperature in the tank. In addition, they protect your fish from random spikes and dips in temperature, keeping it consistently at a safe and comfortable level.

However, when it comes to selecting the best aquarium heater, there are a couple of factors that need to be taken into account. What size is your tank? What type of aquarium heater is best suited to your needs? Do you require the heater for a freshwater or saltwater tank? Are you familiar with the placement, installation, and maintenance process required for different types of heaters? These are all aspects you need to be well-informed about before you set out to buy an aquarium heater.

Top Rated Aquarium Heaters: Key Reviews

Shopping for a fish tank water heater can be frustrating – there are so many products to choose from, with multiple confusing terms and features thrown into the mix. However, our top-rated aquarium heater reviews will simplify the entire process for you, by presenting you a selection of the very best the market has to offer. Read on for our tank water heater reviews for the top 10 heaters.

1.Aqueon Pro Heater Aquarium Heater

Aqueon Pro Heater Aquarium Heater

The Aqueon Pro Heater Aquarium Heater is perfect for pet owners looking to provide a safe and comfortable environment for their fish. It helps reliably regulate the temperature in your fish tank, so you can rest easy in regards to the well-being of your pets.

This 250 Watt aquarium heater is suitable for tanks up to 90 gallons and comes with multiple standout features. Most notably, it boasts an incredibly sturdy and durable construction – this tank water heater is shatter-proof, and has a non-corrosive shell, which makes it strong and perfect for both saltwater and freshwater tanks.

It is fully submersible, which means it ensures even and complete heat distribution throughout the tank. It is also incredibly easy to mount and position horizontally or vertically, according to your needs (just ensure you do not place it too close to the gravel at the bottom of the tank).

The Aqueon Pro Heater also has a bunch of nifty features for adjusting and keeping tabs on the water tank temperature. It has an adjustable heat setting (68 to 88°F), an electronic thermostat which has a control accuracy of +/- 1°, and an LED power monitor light which always remains on – this light turns red when the unit is heating up, and green when it has reached the selected temperature. An Auto Shut-Off feature also ensures that the system shuts down when any over-heating is detected, and the unit also resets itself every time it cools down.

Best of all? This water tank heater comes with a limited lifetime warranty, to ensure maximum customer satisfaction.


  • Durable, shatter-proof, non-corrosive construction
  • Electronic thermostat for accurate reading
  • LED power indicator light
  • Fully submersible


  • The heater may not be as effective if mounted at an angle – horizontal or vertical mounting will work best.

The Aqueon Pro has won over numerous customers, as is obvious by the glowing 5-star reviews it has received online. DC says this aquarium heater works perfectly at keeping the tank temperature at a steady and constant mark. It has “solid construction” and mounts easily. The “accurate dial” ensures you can track the temperature at a glance, and the LED light is super easy to see. Overall, the product is completely “worth the money”! Edward Szubinski is equally pleased – he claims the product comes at a “great price”, is reliable as it keeps the tank temperature perfect, and is “good-looking” to boot.

2.EHEIM Jager Aquarium Heater Review

EHEIM Jager Aquarium Heater

Fish owners can rest easy with an EHEIM Jager Aquarium Heater keeping their fish comfortable and healthy. This unit ensures that the temperature of the fish water tank is regulated and constant at all times.

The EHEIM Jager Heater can be used for both freshwater and saltwater tanks and comes packed with plenty of great features. This unit is fully submersible, which allows for even and complete heating. It comes with a mounting bracket and suction cups, for easy, secure, and flexible positioning within the tank. Its extra-long 5.6ft power cord is an added bonus.

This adjustable aquarium heater is built to last, featuring a shock-resistant and shatter-proof glass construction, which enlarges the heating surface and allows for greater and more even heat distribution. The laboratory-grade glass is free from all kinds of pollutants, resistant to all sorts of chemical and biological substances, and can undergo extreme fluctuating temperatures.

The EHEIM Jager Aquarium Heater features a TruTemp Dial – with a control accuracy of +/- 0.5° C, this dial can be used to make super-precise adjustments to the tank temperature, from 18° to 34° C (65° to 93° F). It can also be used to recalibrate the heater, for more precise temperature regulation and readings.

This aquarium heater also comes with a Thermo Safety Control, which ensures that the heater does not run dry. If it is taken out of the water, it will stop working immediately, and only resume functions once it is back in the water. This means it will automatically turn off if the water level drops too low.

Finally, this unit also features an on/off indicator light, for quick, easy and accurate temperature monitoring, without having to get your hands wet. Eheim Jager is also one of the best aquarium heater brand.


  • Fully submersible – includes mounting bracket and suction cups
  • Shock-resistant and shatter-proof glass construction
  • TruTemp dial for precise temperature adjustment and recalibration
  • Thermo Safety Control


  • The aquarium heater is slightly big in terms of size, but this should not be a problem if it is carefully positioned

The EHEIM Jager Aquarium Heater has many loyal customers to its credit. According to Jonny J., this heater is great at holding “a good, steady temperature”. It is “reliable”, holds true to the dial setting, and best of all it comes at a great price. Scott S. is equally pleased with this aquarium heater – not only is it more accurate than most other models in the market, it also ensures the temperature remains steady throughout the tank, and has, overall, been a “great” buy.

3.Tetra HT Submersible Aquarium Heater Review

Tetra HT Submersible Aquarium Heater

The Tetra HT Submersible Aquarium Heater is the perfect way to ensure the temperature in your fish water tank is at an optimal level for your pets’ comfort and well-being. Ideal for aquariums of 2-10 gallons capacity, this 50 Watt aquarium heater is a great way to keep your fish happy.

This one of the best aquarium heaters comes with lots of great features. It comes with a built-in, electronic, low-voltage thermostat, which automatically maintains the water temperature at 78° F (the ideal temperature for most tropical fish). This means all you need to do is install it, plug it in, and let it get to work – no temperature adjustments required!

The Tetra HT is fully submersible, and fish owners have the option of installing it both vertically and horizontally. Its small size means it can easily be concealed in the tank (for aesthetic reasons, or otherwise), by installing it behind plants or another décor (just make sure it isn’t actually touching any of those items).

This submersible water heater with thermostat also comes with indicator lights, which allow for easy temperature monitoring. When the unit is heating, the lights will turn red; when the proper temperature has been reached and the heater is on standby, the lights will turn green. This aquarium water heater with thermostat will also shut down automatically if an electrical short is detected, for added safety.

The manufacturers recommend that all fish owners read the instructions before using the product, do not switch the unit on when it is not submerged in water, buy a heater suitable for their tank size, and ensure the tank has a hood or glass canopy, to ensure the heat is contained within the aquarium.


  • Built-in automatic thermostat – no adjustments required
  • Fully submersible
  • Indicator light for easy temperature tracking
  • Small size – can easily be concealed


  • Since the thermostat cannot be adjusted, the heater can only be used for fish which require a temperature of 78°F. However, this is ideal for all tropical fish owners

The Tetra HT Submersible Aquarium Heater has proven to be a hit among fish (particularly Betta) owners. Shelly B. says the unit “works beautifully” for his 5-gallon tank, maintaining a consistent temperature at all times. After installing the heater, his previously sluggish Betta has now become active and playful. The effectiveness, combined with the “low price”, makes it a product he would highly recommend. Tina loves how easy the heater is to use, considering there are no adjustments required. Calling it a “great buy”, she says the heater has made her Betta fishes more active and happier, consequently making her feel like a better pet owner. The “great price” is the cherry on top of the cake.

4.Cobalt Aquatics Neo-Therm Aquarium Heater Review

Cobalt Aquatics Neo-Therm Aquarium Heater

The Cobalt Aquatics Neo-Therm Aquarium Heater is ideal for fish owners looking for a sleek, simple, easy-to-use and high-quality contraption that will allow them to regulate fish tank temperature to suit their pets’ requirements. If your prime concern is the comfort of your fishes, this aquarium heater is the one to buy. It’s also one of the safest aquarium heater.

The Cobalt Aquatics Neo-Therm Aquarium Heater comes with a number of standout features. These 75 Watt fish tank water heaters are electronically controlled and submersible – positioned in the water, they ensure even and consistent heating throughout the aquarium, and are suitable for tanks with a capacity of up to 20 gallons.

This tank heater with thermostat also features a sleek, modern, super-flat design, which is aesthetically pleasing and also takes up minimal room in the tank.

The Cobalt Aquatics Neo-Therm has an electronic thermostat, which is super accurate. This heater also has an easy to set One Touch system, to allow for quick and convenient adjustments. The temperature can be set up to a range of 96F, and the design features thermal protection circuitry for added safety. Conveniently, the LED displays both the set temperature and the tank temperature side by side, to allow for precise temperature monitoring.

The unit comes with a 3-year warranty to sweeten the deal and is made in Europe.


  • Fully submersible
  • Modern, flat design
  • Easy to set One Touch system
  • LED simultaneously displays set temp and tank temp


  • Some customers report that the unit came with just one suction cup – however, customer service can be contacted to remedy the situation immediately

The Cobalt Aquatics Neo-Therm Aquarium Heater has worked like a charm for countless happy customers. Zach says he “couldn’t be happier” with this heater, which maintains a steady and consistent temperature, with the biggest temperature variance noted over 48 hours being +/-0.2. The display is super easy to adjust and read at a glance, and the unit is perfect for pet owners who have expensive and/or sensitive tropical fish. Josh Steele had similar words of praise, calling it the “best heater” he has used to date. It maintains temperature reliably, is “super simple” to set up, and conveniently easy to read, involving zero confusion or guesswork.

5.Hydor In-Line External Heater Review

Hydor In-Line External Heater

The Hydor In-Line External Heater is ideal for fish owners looking for a heater that provides precise and consistent temperature control options, to ensure that fish remain comfortable and healthy.

These in-line heaters come packed with plenty of great features. They boast high precision electronic temperature control – an easy-to-use adjustment knob, and an in-built thermostat guarantee full and accurate control over the temperature in your fish tank.

This 200 watt aquarium heater is also the first type of external aquarium heater with PTC technology – they are equipped with a self-limiting PTC heating element that protects from overheating. The safety of your fish (and your house from a possible fire) is a huge plus.

These heaters are designed for external use, which means they can conveniently be installed out of sight, keeping your aquarium beautifully unobscured. They are meant to be used on return lines from external canister filters or sumps, include a 5/8 inch hose, and are incredibly easy to set up and use.

Lastly, the Hydor aquarium heater is suitable for usage with both freshwater and saltwater tanks, making it the ideal choice for pretty much all kinds of fish owners


  • High precision temp control
  • PTC technology for maximum safety
  • Suitable for both freshwater and saltwater tanks


  • While installation might take a little longer than it does with other heater types, the effectiveness of this heater makes it worth it.

The Hydor In-Line External Heater has received rave reviews online. D. Stamatis gives the heater 5 stars, stating that it works great, and sits conveniently underneath the tank. Not only does this mean that it remains out of the way, it also doesn’t compromise the beauty and aesthetic appeal of the aquarium. Frank Hinojos is equally impressed, claiming this is the best heater he has ever used. He says he has been using one for more than 3 years “without ever touching the dial”, and it still works like a charm. In addition to the fact that it gets the job done, it is also great to have a heater that is outside the tank and out of sight.

6.Finnex Aquarium Titanium Aquarium Heater Review

Finnex Aquarium Titanium Aquarium Heater

The Finnex Aquarium Titanium Aquarium Heater is ideal for fish owners looking for a sturdy, durable, and reliable aquarium heater for their pets. A powerful 500 Watt heater, this product is designed to be used for aquariums of up to 120 gallons.

The Finnex compact electronic titanium heater has plenty of useful standout features. Its precision electronic control (thermostat) means you can reliably set accurate temperatures as per the needs of your fish. The best part is that the temperature controller is external (with a hang on hook for convenience) – this means no fishing around inside the tank to try and adjust the temperature. You can change settings easily without getting your hands wet or disturbing your pets.

This submersible water tank heater maintains water temp within +/-2ºF of your set value, ensuring the tank temp remains safe and stable. The design also incorporates an LED heating indicator, which lets you know when the heater is functioning.

In addition to its precision, this heater is also built to last – the titanium heating tube is virtually indestructible, and corrosion-resistant to boot. It can be used for both fresh and saltwater tanks and heats up super-fast. Its compact size also makes it easy to hide in the tank for aesthetic purposes.

The titanium heating tube is encased in a protective heater guard, to keep both your fish and the surrounding equipment safe. The guard also has suction cups attached, for easy placement. Overall, this is the best titanium aquarium heater currently available in the market.


  • External precision electronic control (thermostat)
  • Strong titanium heating tube
  • Protective heater guard for safety
  • LED heating indicator


  • The warranty situation is not completely clear

The Finnex Titanium aquarium heater has proven to be a popular choice among fish owners. Janngogh says this is a very “dependable” heater, which can be set and left alone without having to worry. It maintains a constant, dependable temperature, and the external controller is great because you don’t need to keep reaching inside the tank to make adjustments, which can stress out the fish. Kelly S. Parker is also pleased with the heater, saying it “works great”, runs continually, and overall “feels well made and safe”.

7.Aquatop Aquarium Heater Review

Aquatop Aquarium Heater

The Aquatop Aquarium Heater is the ideal choice for fish owners who want a heater that will maintain constant and stable temperatures, allowing their fish to thrive.

This 50 Watt heater is suitable for tanks of up to 13 gallons in capacity and comes packed with lots of useful features. Temperature control is incredibly precise, with a range of 68-93F. The temperature setting is easy to use via a temp adjustment knob and provides the option of measuring in both Fahrenheit and Celsius. In addition, the temp setting is highly visible, making it easy to read and monitor the temperature.

The heater also features double insulation and is made from high quality insulated glass. It is fully submersible and suitable for both freshwater and saltwater tanks. The unit comes with suction cups, which make for quick, easy and secure installation.


  • Easy to use temp control
  • Made from high quality insulated glass
  • Suction cups included


  • The product is only effective for tanks with a 13-gallon or less capacity

The Aquatop aquarium heater has proven to be an excellent and reliable purchase for countless customers. Melissa Collins says the temperature display is “very clear” and a comfortable print size which makes for easy temp monitoring. The option to measure temperature in both Fahrenheit and Celsius is an added bonus. The suction cup for attaching the heater is super strong, and the heater warms up quickly. Rose D. says the heater is “worth the money” – it is inexpensive but gets the job done nicely. It keeps the temperature constant, and she has been using it for more than 4 years without any trouble.

8.Penn Plax Submersible Aquarium Heater Review

Penn Plax Submersible Aquarium Heater

Keeping your fish warm, comfortable and healthy has never been as easy as it is with the Penn Plax Submersible Aquarium Heater. Providing reliable and accurate maintenance of tank water temperature, this heater comes with a 3-year warranty, and a 100% satisfaction guaranteed, money back guarantee. This heater, which is suitable for tanks up to 75 gallons in capacity, has multiple standout features which make it a winning product. Most notably, it provides highly reliable and precise temperature control – it sets and maintains the temperature within 1-degree accuracy. Setting your desired temperature is easy thanks to the user-friendly dial knob.

The gage is also super easy to read, and features temperature measurements in both Fahrenheit and Celsius. The heater comes with a preset temperature to 76 degrees, but it can also be programmed rather easily if required.

This 300-watt aquarium heater is made with superior insulation and ensures even heat distribution throughout the tank. Its heavy-duty shock-resistant glass makes it durable, long-lasting, and safe to place in a tank with your aquatic pets.

The heater is fully submersible, and is incredibly easy to install and setup – it can be mounted both vertically and horizontally in the tank and comes with dual suction cups and mounting clips for secure placement.


  • Accurate to 1 degree
  • Easy-to-read gage with both Fahrenheit and Celsius temperature
  • Fully submersible


  • The heater is designed for use under water, so it needs to be handled with utmost care before it is placed inside the aquarium.

The Penn Plax Submersible 300w aquarium heater has received countless 5-star reviews online. Sarah V. says this heater is easy to set up, affordable, and works as desired. The size is not too large or awkward, and her fish seems comfortable and happy. Jared Arand praises the heater for being incredibly “reliable”, stating that it never malfunctions, and keeps the water temperature maintained at a steady and stable level.

9.Aqueon Submersible Aquarium Heater Review

Aqueon Submersible Aquarium Heater

If you’re looking to keep the water in your fish tank warm and comfortable for your aquatic pets, the Aqueon Submersible Aquarium Heater is all you need. This 150 Watt heater works wonders for fish tanks up to 55 gallons in capacity.

The Aqueon submersible aquarium heater has plenty of great features going for it. These heaters are incredibly durable, thanks to their thermal shatter-resistant quartz glass construction, which enables them to absorb all kinds of impacts. They are also fully submersible, can be positioned both horizontally and vertically, and are suitable for use in both saltwater and freshwater tanks.

This 150 watt aquarium heater also allows for precise temperature control to 1-degree, within a range of 68-88 degrees F. It is UL approved, and programmed to automatically turn itself off when not submerged properly, to protect from overheating and any subsequent damage. It also features an Aqueon heater indicator light, which turns on every time the heater is on.This submersible fish tank heater comes with a limited lifetime warranty and a 6-foot power cord for easy placement and positioning.


  • Durable shatter-resistant construction
  • Precise temp control with automatic shut-down feature to prevent overheating
  • Limited lifetime warranty


  • This heater cannot be used for larger tanks that are more than 55 gallons in capacity

The Aqueon submersible aquarium heater has earned rave reviews online. Hannah K. Ritter says this heater “works great”. She says the suction cups that come with it are a nice bonus, and the heater ensures even heat distribution. It is not fragile, the dial is easy to adjust, and it takes no time to get the tank nice and warm. Joel has similar words of appreciation for the heater, claiming it comes at a “good price” and offers good value for money. The length of the cord is great, and the tank remains steady at the set temperature. In addition, the indicator light which lets you know when the unit is heating up is very useful.

10.Marineland Aquarium Heater Review

Marineland Aquarium Heater

The Marineland Aquarium Heater gives you precise and complete control over the temperature of your water tank. The result? Happy, healthy, and comfortable fish. This is a pretty great option if you are looking for the best cheap heater.

This 100 Watt aquarium heater is suitable for aquariums of up to 29 gallons and comes with multiple great features. Its adjustable temperature dial ensures that you can set the temperature in the tank as per your specific requirements, 1 degree with each click.

The advanced heating element – a mica core enveloped with a mesh heating element – ensures superior and thorough heat transfer evenly throughout the tank, with added durability. It keeps the tank at an optimal temperature. The design also features a Thermal Switch, which automatically turns the heater off when the temp rises above a preset level and turns it back on once it has cooled down – this ensures the safety of both fish and their owners. The high visibility temperature display of the Marineland heater is another great feature – the easy-to-view sliding scale can be consulted for accurate temperature settings, and the top dial view allows fish owners to view the setting from a different angle. In addition, this 100-watt aquarium heater comes with an advanced mounting bracket, which attached to the glass securely with the aid of durable suction cups – 3 window positions are available for viewing the temperature display.


  • Adjustable temp dial with 1 degree accuracy
  • Thermal switch for added safety
  • Quick and superior heat transfer
  • High visibility temp display


  • The warranty situation is murky – however, greater clarity can be gained by contacting the company

The Marineland aquarium heater has countless loyal fans online. Jesse says the heater keeps the fish tank water at a “great” steady and reliable temperature. It works wonders for the fish and attaches to the desired location nicely and without any fuss. It is reliable and easy to “set and forget”. Madeline Krajecki, meanwhile, says the heater is “perfect”. Considering the usual prices of aquarium heaters, this heater is relatively cheap and super precise.

Aquarium Heaters Buying Guide

An aquarium heater is a must for any fish owner with a tropical aquatic pet, any other fish species that require warmer temperature, those whose fish tanks are placed in rooms/locations that tend to be colder, and pet owners who live in areas that experience harsh winters.

However, the actual purchasing process can be quite difficult and confusing. Being overwhelmed by the wide variety of products on offer, being ill-informed about the different types of heaters and their specific usages, being unaware of factors such as size, heater placement, installation, and maintenance – these are all problems that can steer you toward making the wrong decision, and ending up with an inferior-quality and/or unsuitable aquarium heater. But what is the best aquarium heater? What features does it need? Are all aquarium heaters submersible? Let’s see.

To aid you in the process, we have compiled a useful buying guide for aquarium heaters, to help you breeze through the selection process and ensure that you are well-informed on all aspects of purchasing a fish tank heater. After you’ve been through our guide, you’ll be able to make the right decision and select a top-quality fish aquarium heater that is perfectly suited to your requirements and the needs of your fish.

Benefits Of Aquarium Heater

If you are wondering “do I need a heater for my fish tank”, this is your answer. Fish may seem like they don’t need much and that’s partially true – unlike more high maintenance pets like dogs and cats, there’s no walks to be taken, no litter to be scooped, and no coat to be brushed.

However, fish do require special, specific types of care, the negligence of which could have fatal consequences. One of the key factors you need to take into account for the health and comfort of your pet is temperature, and the key benefit of an aquarium heater is that it helps fish owners regulate the temperature in an aquarium.

Fish are poikilothermic, or cold-blooded, which means they do not produce their own body heat and their internal/body temperature changes according to the temperature of their surroundings. They are sensitive to the environment and need a specific external temperature in order to be able to survive in fish tanks.

The temperature fish require depends on their species too – bettas, and other types of tropical fish, for example, need warmer water temperatures in order to survive. While some fish are able to survive in room temperature water, there is no guarantee that the water will remain at that temperature, especially if you live in an area that experiences harsh winters. This is why an aquarium heater is not only beneficial but necessary for all fish owners, regardless of the species of the fish.

Aquarium Heater Size Calculator & Guide

Aquarium heaters come in a wide range of sizes, and determining the right size for your aquarium is a crucial step of the decision-making process. It may seem like a daunting task involving complicated calculation, but we’ve broken it down for you and compiled a simplified aquarium heater size guide and an aquarium heater size calculator.

Basically, calculating the correct heater size for your aquarium requires two simple points of information – the temperature of the room in which your aquarium is placed, and the volume of water in your tank, i.e. tank capacity.

First, to determine the aquarium heater wattage you require, use your aquarium’s capacity/volume – calculate 2.5 to 5 Watts per gallon of actual water volume in your fish tank. For example, a 10-gallon tank will require a heater size of 25 Watts.

Next, determine the amount of heating you need – this can be calculated by subtracting the average temperature of the room in which the aquarium is placed from the temperature you want your aquarium water to be. For example, if the average temperature in the room the aquarium is located in is 62 degrees Fahrenheit, and you need the water in the tank to be at a temperature of 79 degrees Fahrenheit, the amount of heating you require is 15 degrees Fahrenheit.

Then, proceed to use the chart below to determine the heater size/Wattage you need. Find your tank volume (i.e. capacity) on the left-hand column, and then look for the column which lists the amount of heating you require (which you previously calculated). If your heating requirement is in between the levels listed, simply move to the next larger size.

(Keep in mind that when tanks are on the larger side, or temperatures are on the lower side, you might need to use two heaters, spaced far apart to ensure even heat distribution throughout the tank).

Tank volume – Heat 9°F/5°C – Heat 18°F /10°C – Heat 27°F /15°C

5 gallons/25 liters – 25 Watt – 50 Watt – 75 Watt

10 gallons/50 liters – 50 Watt – 75 Watt – 75 Watt

20 gallons/75 liters – 50 Watt – 75 Watt – 150 Watt

25 gallons/100 liters – 75 Watt – 100 Watt – 200 Watt

25 gallons/100 liters – 100 Watt – 150 Watt – 300 Watt

25 gallons/100 liters – 150 Watt – 200 Watt – 2x 200 Watt

25 gallons/100 liters – 200 Watt – 250 Watt – 2x 250 Watt

25 gallons/100 liters – 250Watt – 300 Watt – 2x 300 Wat

If you’d rather obtain a quick, automatic answer for the heater size you need, you can use a calculator such as this one, or this one, to determine the most suitable heater size for your aquarium.

Where To Place The Fish Tank Heater

The purpose of an aquarium heater is to heat up the tank – therefore, the aim of correct heater placement in a fish tank should be even and uniform heat distribution. If you are wondering “where to place aquarium heater”, here are some tips for fish tank heater placement.

Ideally, the best place for an aquarium heater is that a heater should be placed as close as possible to the water flow without obstructing it – e.g. the outlet or inlet from your filter, or horizontally directly above the gravel close to the filter discharge if it is a fully submersible heater. The main method for heat transfer in an aquarium is circulation, and when water flows past the heater, heat is dispersed quickly and more evenly throughout the tank. Of course if your tank is large, consider placing two smaller heaters at opposite ends, as this will also ensure more even heat distribution.

Aquarium heater placement also depends, largely, on the type of heater you purchase – for example, a submersible heater will be placed inside the tank, an immersible/hanging heater will be hung off the top edge of the fish tank, substrate heaters will be buried in the aquarium gravel, in-line heaters will be connected to external plumbing, and in-sump heaters will be connected to the sump.

For internal heaters (which are placed inside tanks), some general placement precautions would include avoiding placing the heater close to décor, or placing it in a way that fish might trap themselves or get burnt.

For external heaters, ensure all pipes/connections are properly connected, and avoid placing them in a manner that might lead to them being disturbed or knocked about by passersby – they should be placed safely out of harm’s way.

How Much Electricity Does An Aquarium Heater Use?

Most fish owners will have concerns about the amount of electricity that an aquarium heater consumes, since it needs to be plugged in and remain turned on at all times.

There is no sure way of knowing exactly how much electricity aquarium heaters generally consume – this depends on a variety of factors, such as the type of heater you choose, the brand/model of your heater, the size of your tank (the larger it is, the more expensive it will be to keep heated), and even the species of your fish (tropical fish require warmer temperatures, leading to more expense).

However, by using the size of your tank, and the temperature at which you set it, you can gain a rough idea about the amount of electricity your aquarium heater might be using. For example, a tank with a capacity of 30 gallons, when heated to 72F, will consume about 110 kWh per year. A tank of the same size, when heated to 82F, will consume around 440 kWh per year.

Types Of Aquarium Heaters

While they all have the same function – i.e. to warm up the water in your fish tank – aquarium heaters come in different types. Generally, there are two main types of aquarium heaters – internal heaters (which are installed inside the fish tank itself) and external heaters (which are located outside the fish tank).

There are three types of internal heaters – immersible/hanging, submersible, and substrate – and three types of external heaters – in-line, in-filter, and in-sump. However, all types require a thermostat, to allow pet owners to adjust the temperature as desired. Here, we’ll discuss some of the key characteristics of each type, so you can determine which type best suits your requirements and the needs of your aquatic pets.

Immersible Heater

These types of aquarium heaters are generally the least expensive type, and most aquarium kits come equipped with this type of heater.

Immersible heaters are also known as hanging heaters, since they are positioned so they hang off the edge of the top of the aquarium (generally at the back), while the heating element (usually a glass tube) is placed in the water. The temperature controls remain outside the water.

An opening in the aquarium hood is required to install this type of heater (most hoods already have an opening to accommodate this type of heater).

While the price makes them an attractive option, care needs to be taken for the safe usage of immersible heaters. They need to be installed securely, to ensure they do not get knocked about or bumped into, as this can cause the glass covering of the heater to break, leading to electrocution, and possibly even a fire.

These types of heaters are also best suited as freshwater aquarium heaters – saltwater can cause corrosion, and lead to electrical shorts.

Submersible Aquarium Heater

These are generally the most popular type of aquarium heater. Since they can be fully immersed in the water, they tend to be more effective heaters than the hanging variety. They are usually installed with the aid of suction cups, and can be positioned lower down in the tank – vertically, horizontally, or diagonally. However, care needs to be taken so they do not actually touch the gravel or any other décor pieces, as this will interfere with heat conductivity. They should also be positioned so fish cannot get trapped against them or burned.

Some submersible heaters have an internal thermostat, while some come with an external temperature controller (these tend to be more convenient). While they are pricier than the hanging variety, their effectiveness makes them well worth the price. In addition, the smaller-sized varieties can easily be concealed, for aesthetic purposes.

Substrate Heaters

These are the least common type of internal aquarium heaters in North America, although they are used widely in Europe. Substrate heaters comprise either a coil or a number of cables/wires enclosed in an insulator, which are installed underneath the aquarium gravel or substrate. When turned on, the coil/wires heat the gravel, which then radiates heat to warm the water. When the water reaches the desired temperature, the thermostat switches off.

While this type of heater is bothersome to install (everything needs to be taken out of the aquarium to put them in), they are extremely effective once put into place, and are also great from an aesthetic point of view, since everything is hidden from sight.

Inline Aquarium Heater

An inline fish tank heater is a type of external, self-contained aquarium heater, which is installed in or along the external plumbing for some aquarium equipment (such as a filter). A water pump is generally required to push water out the tank, through a pipe or tube, and through the heater, after which it is warmed and pumped back into the tank.

You can eliminate the need for a separate water pump by hooking an inline aquarium heater up with a piece of equipment such as a trickle filter or UV sterilizer, which will ensure water flow through the heater without a dedicated pump.

These types of heaters can be a bit tricky to install, but they are incredibly effective, and the best part is that both your fish and heater stay safe, since there is no contact between the two.

In-filter Heater

These types of aquarium heaters come built into the filter system of the fish tank, for added convenience; they are usually incorporated with canister filters and power filters, and are integral to the design and functioning of the filter. As water passes through the filter, it is heated by the heater, and then returned to the tank both warmed and cleaned. Since they are part of the filter, no additional set-up is required, and there are no clunky, additional heaters obscuring the beauty of your aquarium. However, with some models, temperature control may be tricky.

In-sump Heaters

These types of aquarium heaters are submersible heaters that are located in the sump of a trickle filter. The benefits are similar to those obtained with inline aquarium heaters – since the heater is located outside the tank, aggressive fish cannot damage it, nor can it cause injuries or burns to your pets. However, they may be easier to maintain than inline heaters.

Mini heaters

These are small-sized heaters that are used to heat small tanks or fish bowls, instead of large aquariums. They come in particularly handy for fish like Bettas, which are sometimes kept in bowls (the ethics of this may be debatable, but is irrelevant here). These types of heaters have recently been introduced, and while they may be convenient, they can be challenging to use, since they may not heat the water fully or effectively.

Heating Freshwater vs Saltwater Tanks

There are no major differences in regards to the heating between a freshwater tank heater and a saltwater tank heater. The only factor fish owners should take into consideration is that the heater they purchase needs to be safe for use in saltwater/brackish water – the best saltwater aquarium heater will be corrosion and rust free. Some designs and materials are ill-suited to saltwater since the water can cause rust or corrosion. Immersible heaters, for example, aren’t the best idea for saltwater tanks, since salt can get into the tube, leading to corrosion, or an electrical short which can be highly dangerous. Generally, the packaging of an aquarium heater will specify which type of tank it is to be used for, and fish owners need to take this into serious consideration when selecting an aquarium heater.

How To Install Aquarium Heater

The installation process for tank heaters differs according to the type of heater you select – the process of installing a submersible heater, for example, will be vastly different from the process of installing an inline heater. Each type of heater comes with its own instruction manual, and these need to be read carefully, for the safe and efficient installation of you heater of choice.

However, here are some general guidelines that can be followed for how to install aquarium heater:

  • Start by removing your fish from the aquarium to a safe location, and turning off the aquarium (but do not empty it).
  • Examine the location where your aquarium is placed. Check for any surrounding sources of intermittent heat/cold, and any fluctuations in temperature that might occur. If you feel the location does not allow for a steady and comfortable temperature to flourish in the fish tank, consider re-locating the aquarium.
  • Next, examine your heater before you start the installation process – ensure that the casing is intact, and there are no signs of cracks, exposed wires, or any other kind of damage. In addition, keep in mind that heaters should not be turned on until AFTER they have been securely installed.
  • Scope out the location where you plan to install the heater – it should be an algae-free location where there is plenty of adequate water flow, for optimal operation and uniform heat distribution. If you plan to use internal heaters, you will want to check the insides of the tank, while for external heaters, you’ll need to examine the equipment you will be attaching the heater to. For example, for immersible heaters, you’ll need to look for space at the back and ensure there is an appropriate hole in the aquarium hood. Ensure that your location of choice is clean and intact.
  • Next, use the method prescribed in the instruction manual to install/attach the heater. For example, for inline pumps, you will need to hook the heater up to the return lines from external canister filters or sumps; and for a submersible heater, you will need to mount the device on the aquarium walls using suction cups in the prescribed position. Double check to ensure the heater is properly attached.
  • When installing, make sure the heater is not obstructing any other equipment, and not blocking the path of your fish. Internal heaters should also not be touching plants or décor (with the exception of substrate heaters, which will naturally be touching the gravel) as this may cause electrocution or fires, nor should they be positioned in such a manner that fish might get trapped against them and receive life-threatening burns. Make sure that there are plenty of other, more attractive places to hide in the aquarium, so your fish don’t feel the need to swim around the heater.
  • Allow the heater to rest for 30-45 minutes, especially if it is an internal heater – internal heaters need time to adjust to the surrounding water temperature (if they are suddenly turned on, they may crack). Similarly, you will need to ensure the heater has been unplugged for at least half an hour before you drain the tank and remove it from the water if you choose to do so later on.
  • Slip an external thermometer into the aquarium water – this is so you can get a reading from a second source, and ensure that the heater is working correctly. Read and note the initial reading of the water.
  • Then, turn the heater on, and adjust it to the temperature you require. Let it run for 24 hours, and check the thermometer every 4 hours, to ensure the heater is working properly. During this time, you will also get a feel for how the heater and its settings work.
  • Finally, when you have ensured the heater is working properly, add your fish back to the water.

Note that it is generally recommended to use an aquarium cover – this helps retain heat and prevent temperature variances which can stress your fish out and be detrimental for their health.

If installing submersible heaters in a large tank, consider using multiple units – this allows for more even heat distribution, prevent the units from getting too strained, and allow the temperature to remain steady even if one goes out. Another recommendation is to keep an extra heater or two as a back-up, in case one stops working.

Fish Tank Heater Maintenance

Just as you clean and maintain your aquarium, heaters need regular cleaning and maintenance too. This is essential for their smooth and proper functioning – not only will regular maintenance increase the life of your heater, it will also give you greater peace of mind, ensure the health and well-being of your aquatic pets, and keep both you and your pets safe from hazards such as electrocution or fires. There is nothing worse than discovering your heater has killed your beloved pets owing to a malfunction which caused over/under-heating, and these malfunctions are usually owing to lack of maintenance.

Most obviously, it is a good idea to buy a heater that is of top quality, and easy to clean to begin with. The trickier a heater is to clean, the more likely you are to avoid it, and the more likely that you might break it (tank heaters are very fragile) or disturb its components during clean-up, leading to malfunctions.

Reading the instruction manual that comes with the heater is the best way to get up to speed on how to clean your aquarium heater.

Generally, the first step would be to turn off the heater (make sure you use a replacement heater to keep the water at a comfortable temperature for your fish while you go about the cleaning process). Next, you will need to use the recommended equipment and prescribed procedure to clean the heater. It is especially important to clean regularly if you have a saltwater aquarium heater (salt can build up inside heaters, leading to corrosion, overheating, and electrical shorts), and remove all build-up such as algae. Once the cleaning process is completed, the heater can be reinstalled and used.

During usage, consider using a heater guard to protect your heater and avoid breakage. Do not ever attempt to take it apart, and if it malfunctions, either discard it and get a new one (this is the best, most recommended option), or take it to a professional instead of attempting to fix it yourself.

In addition, it is always a good idea to keep a spare handy, in case your main heater breaks, especially during crucial times such as winter, or with especially sensitive fish.



Ultimately, the best aquarium heater is the one that is best suited to the needs of a particular user and his/her aquatic pets. To make the best decision for yourself and your fish, you need to be informed about which aquarium heater type and size to select, how to install, place, and maintain the heater, and how best to benefit from it. All this information, and more, has been outlined in our guide on buying the best aquarium heater, to ensure you make the best, most well-informed decision.

Buying an aquarium heater is essential if you’re looking to keep your fish healthy and comfortable – they are especially necessary for fish that require warmer temperatures (such as Bettas), and are sensitive to fluctuations in temperature. Without a heater, your fish may get sick, suffer from stress, and even die. By buying and installing an aquarium heater, you can be sure you’ve done the best you can to ensure your pets’ well-being.

Purchasing an aquarium heater requires pet owners to take countless factors into account. No one wants to be stuck with an inferior quality heater – they can malfunction, burst, overheat, and even stop working altogether, all of which can lead to dire consequences for your pet, and even you and your family. This is where our top aquarium heaters reviews and aquarium heater guide come in handy. In order to be assured that your heater is safe and suitable, you need to make sure it is well-suited to the size of your tank. You will also need to weigh the pros and cons of different types of heaters, and pick the one you think will work best in your circumstances/with your aquarium and equipment. It is also essential to be well-informed about the procedures for installing and maintaining fish tank heaters, as this will help you anticipate what you will need to do once you have purchased one.

Taking all factors into account, if you’re looking for the most reliable aquarium heater, our top pick for the best aquarium heater is the Aqueon Pro aquarium heater. This is our answer to the question “what is the best aquarium heater”. Regulating the temperature in your fish tank cannot get safer and easier than it is with this heater. This heater is 250 Watts and works perfectly for tanks of up to 90 gallons. Its durable construction features a shatter-proof and non-corrosive shell, which means it will last you long, whether you use it in a freshwater tank or a saltwater aquarium.

Since it is fully submersible, it has all the benefits of this type of best aquarium heater – it is incredibly effective, and ensures complete and uniform heat distribution, without any hot or cold spots. Suction cups are included with the package, to make mounting and installing a breeze. Temperature control is easy and effective with the Aqueon Pro. The heat can be adjusted within the range of 68 to 88°F, and the thermostat has a control accuracy of +/- 1°. The LED power monitor light is great for letting you know when the unit is heating up, and when it is on standby after reaching the desired temperature. Its Auto Shut-Off feature is also great for added safety, to prevent overheating. Overall, these standout features, combined with its limited lifetime warranty, make the Aqueon Pro the absolute best fish tank heater in our books.