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The Best Digital Aquarium Heater: Freshwater & Saltwater Tanks

Digital aquarium heaters are a great choice for maintaining an accurate and stable temperature. So let’s find the best digital aquarium heater for your tank!

By Matt Thomas
Last updated on

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best digital aquarium heater

A digital aquarium heater can often be the most accurate and easy-to-use type for your aquarium. And the best digital aquarium heater tends to come with extra features such as alarms to tell you if the temperature falls outside the required range.

After reviewing and assessing some of the best digital aquarium heaters our top choice is the Cobalt Aquatics Neo Therm Pro Heater for its accuracy, compact design, and temperature stability.

But we’ve also assessed several other options, from budget picks to saltwater-specific digital aquarium heaters, so you can find the most suitable for your tank all in one place!

So let’s look at the list…

  1. Best Overall: Cobalt Aquatics Neo Therm Pro Heater
  2. Best Budget Pick: AQQA Aquarium Heater
  3. Best For Saltwater: Hygger Saltwater Titanium Aquarium Heater
  4. Best For Small Tank: FREESEA Submersible Heater
  5. Best For Large Tank: Hygger Digital Titanium Aquarium Heater
  6. Best For Temperature Alarm: Fluval E Electronic Heater

Best Digital Aquarium Heater Picks Reviewed

We’ve taken into account several key factors when assessing the heaters in this list, including temperature range, accuracy, and auto shut-off features. So you’ll have plenty of options from which to find the best digital aquarium heater for you.

1. Cobalt Aquatics Neo Therm Pro Heater


  • Heater Type: Submersible, adjustable, digital/ electronic
  • Dimensions (inches): 25W/ 50W/ 75W = 6.75 (length) x 2.25 (width) x 1.25 (depth), 100W = 9.75 (l) x 2.25 (w) x 1.25 (d), 150W/ 200W = 11.0 (l) x 2.25 (w) x 1.25 (d)
  • Wattage: 25W, 50W, 75W, 100W, 150W, 200W
  • Key Features: Temperature range of 68 to 94°F, built-in thermostat accurate to +/- 0.5°F, touch-button control, set temperature and current temperature LEDs, automated shut-off to prevent overheating, shatterproof casing
  • Best For: Overall

Our overall choice of the best digital aquarium heater is the Neo Therm Pro from Cobalt Aquatics. It comes in a range of wattages from 25 to 200 Watts, so whether you have a 3 gallon tank or 55 gallon aquarium you’ll find the option you need. And you can even use two for a larger tank.

While these heaters are powerful, they’re also very compact. The smaller 25 to 75 Watt versions are just 6.75 inches long, and the larger 150 and 200 Watt only 11 inches. This, coupled with the fact they are flat, means you can easily disguise them in a small or large tank.

The Neo-Therm is freshwater and saltwater compatible, has a range of 68 to 94°F, and is accurate to +/- 0.5 degrees. So it will suit most fish no matter what you keep. It also maintains a very stable temperature, so once set you can be confident in the environment for your fish.

Adjusting the temperature is simple by using the touch button control, and the Neo-Therm shows the current temperature along with the temperature you’ve set with the clear LEDs. So it’s easy to identify any faults or take action if the temperature needs adjusting.

It also has an auto shut-off which turns off the heater if your tank temperature gets too high. So you’ll have peace of mind that you won’t harm your fish. 

Overall, while this heater does attract a premium price, it receives excellent reviews from customers for its reliability and ease of use. This coupled with the 3-year warranty makes it one of the best digital aquarium heaters available.

2. AQQA Aquarium Heater


  • Heater Type: Submersible, adjustable, digital/ electronic
  • Heater Rod Dimensions (inches): 100/ 200/ 300W = 11.4 (length) x 2.17 (width), 500/ 800W =  11.2 (l) x 3.4 (w)
  • Wattage: 100W, 200W, 300W, 500W, 800W
  • Key Features: Temperature range (100/ 200/ 300W) 59 to 93°F (500/ 800W) 68 to 93°F, shatterproof quartz glass heating element with bumper guard, built-in thermostat accurate to +/- 0.1°F, external LED controller showing current and set temperature, automated shut-off to prevent running when dry, memory function
  • Best For: Budget Pick

The AQQA Aquarium Heater is a great budget choice of digital aquarium heater for a larger tank. It ranges from 100 to 800 Watts making it suitable for tanks around 30 gallons up to about 180 to 200 gallons.

And while powerful, the 100 Watt model is not too long at 11.4 inches. So it will still fit comfortably in a 16-inch high 30 gallon tank. Accurate to +/- 0.1°F, many owners praise the ability of the AQQA to keep their water temperature stable.

The AQQA is compatible with freshwater and saltwater tanks, and the 100 to 300 Watt models have a range of 59 to 93°F. So if you have species that tolerate a lower temperature, such as Paradise Fish (61-79°F), you can set it low to keep the water warm in colder months.

While the shatterproof quartz glass heating rod sits submerged in your tank, the controller is not waterproof so must sit outside your aquarium. But this does make the LED screen easy to read and the temperature very easy to adjust as you don’t need to reach inside your tank.

There’s also a flame torch light that flashes along with the surrounding lights when the unit is actively heating. And once they show steady on, the temperature is constant. So you can easily see when the heater is working and keep an eye out for any faults.

Overall the AQQA heater gets great feedback from owners for its ability to hold a stable temperature, easy-to-use controls, and durability.

3. Hygger Saltwater Titanium Aquarium Heater


  • Heater Type: Submersible, adjustable, digital/ electronic
  • Heater Rod Dimensions (inches): 50W = 8.7 (length), 100W =  9.8 (l), 200W = 10.7 (l), 500W = 12.3 (l)
  • Wattage: 50W, 100W, 200W, 500W
  • Key Features: Temperature range of 32 to 104°F, shatterproof & anti-corrosive titanium heating element, accurate to +/- 0.5°F, external LED controller showing current and set temperature
  • Best For: Saltwater

Made from anti-corrosive titanium, this heater from Hygger is highly resistant to saltwater and perfect if you own a saltwater tank. It comes in sizes ranging from 50 to 500 Watts, so you’ll find one suitable whether you have a 5 gallon tank or a 120 gallon aquarium.

One of the stand-out differences with this digital aquarium heater is its temperature adjustability, from 32 all the way to 104°F, and it’s also accurate to +/- 0.5°F. Perfect if you own a full reef tank with corals or marine fish with a range of temperature needs and sensitivity to fluctuations. 

The external LED controller shows the current and set temperature, which you can clearly see from a few feet away. So it’s easy to keep an eye on your aquarium’s temperature and watch for any possible faults.

Be aware the heating rod does not have its own built-in thermostat, rather there’s a separate temperature probe. So always ensure the probe sits in your tank below the water line, as if you take out the probe the heater will stay on and so could harm your fish.

But overall, this digital aquarium heaters gets plenty of high praise from current owners for its simple operation, durability, and accuracy.

4. FREESEA Submersible Heater


  • Heater Type: Submersible, adjustable, digital/ electronic
  • Dimensions (inches): 50/ 100W = 3.7 (length) x 2.5 (width) x 1.5 (depth) 
  • Wattage: 50W, 100W
  • Key Features: Temperature range of 59 to 94°F, built-in thermostat, LED temperature display, touch-operated adjustment switch
  • Best For: Small Tank

Freesea’s digital aquarium heater is a simple design specifically made for small aquariums. It comes in two sizes, 50 and 100 Watt, and is suitable for 5 gallon tanks up to around 30 gallon aquariums.

Both models are incredibly compact, at just 3.7 x 2.5 x 1.5 inches, so you’ll have no problem fitting the 50W inside a 5 gallon tank without taking up swimming space for your fish. And the temperature range of 59 to 94°F is plenty wide enough to suit most tropical and nano fish.

You can easily adjust the temperature using the single touch-button control, and as it’s located on the cable it means you don’t need to get your hands wet or disturb your fish by reaching inside your tank.

The LED display clearly shows the current temperature, although it only shows the temperature you are setting as you are adjusting it. 

Once your set temperature is reached the built-in thermostat will automatically switch off the heater, so you can be confident you won’t harm your fish. But bear in mind this heater has no auto shut-off if it runs outside the water, so always ensure it’s fully submerged.

Some owners have reported that while the heater has a bumper guard, fish can sometimes get trapped between the suction cups and heater element at the back. You can safeguard against this by wrapping webbing around the suction cups to stop your fish from swimming behind it.

But overall many owners praise this small digital aquarium heater for its ease of use, compact size, and reliability.

5. Hygger Digital Titanium Aquarium Heater


  • Heater Type: Submersible, adjustable, digital/ electronic
  • Dimensions (inches): 500W = 8.6 (length) x 3.4 (width) x 1.0 (depth), 800W = 10.2 (l) x 3.4 (w) x 1.0 (d)
  • Wattage: 500W, 800W
  • Key Features: Temperature range of 70 to 94°F, accurate to +/- 1°F, LED digital display showing current or set water temperature, rapid heating, corrosion-resistant titanium casing, overheat protection, auto shut-off when out of water
  • Best For: Large Tank

Hygger’s Digital Titanium Heater comes in 500 and 800 Watt versions and is suitable for large tanks around 100 to 180 gallons. Note this heater is only designed for freshwater use though, as parts of the heating unit are made of aluminum which saltwater can corrode.

Both models are very compact given the power, with the 500W being just 8.6 inches in length and the 800W only 10.2 inches. So in a large 100 gallon aquarium, you’ll be able to easily disguise it if you wish, and it certainly won’t get in the way of your fish.

It has a large digital display that can show the current or set temperature. So it’s easy to quickly check your tank is in the right temperature range, even from across the room. And the touch control sits outside the tank for easy adjustment without getting your hands wet.

The Hygger Titanium heater has an adjustable range of 70 to 94°F, so is perfect for many tropical fish species given most prefer a range of around 74 to 80°F. 

While it claims to be accurate to +/- 1°F, some owners have reported it can be a degree or so out. So we’d always recommend keeping a separate thermometer in your tank to double-check.

Having said that, the majority of owners praise the Hygger Titanium for its ease of use, compact design, and ability to maintain a stable temperature in large aquariums.

6. Fluval E Electronic Heater


  • Heater Type: Submersible, adjustable, digital/ electronic
  • Dimensions (inches): 100W = 11.75 (length) x 2.0 (width) x 1.12 (depth), 200W = 14.0 (l) x 2.0 (w) x 1.12 (d), 300W = 14.0 (l) x 2.0 (w) x 1.12 (d)
  • Wattage: 100W, 200W, 300W
  • Key Features: Temperature range of 68 to 93°F, adjustable in 1°F increments, two digital temperature sensors, LCD screen with VueTech color alert system, fish bumper guard
  • Best For: Temperature Alarm

Fluval’s E Series digital aquarium heaters come in a range of sizes from 100 to 300 Watts and are suitable for 30 gallon tanks up to around 100 gallon aquariums. They have a range of 68 to 93°F which you can adjust in 1°F increments, so you can cater for most species of fish.

The E Series is compatible with freshwater and saltwater aquariums and has dual temperature sensors helping it maintain an accurate and stable environment for your aquatic life. But it also has the VueTech color alert system for extra peace of mind.

If the temperature falls +/- 2°F outside what you’ve set, the digital display will change color to blue for too cold or red for too hot. So you can easily see any faults or problems and make adjustments as needed.

E Series digital aquarium heaters automatically calibrate themselves, making setup really easy. And there’s a full bumper guard across the whole heating element, so your fish are protected from coming into contact with it.

Some owners report that getting initial placement right can sometimes be tricky. You have to position the heater correctly near your filter’s outflow for correct water circulation. But overall owners praise the E Series for its accuracy and ability to maintain a stable temperature.

Considerations When Choosing A Digital Aquarium Heater

Digital aquarium heaters can sometimes be pricier than analog ones but are often easier to use and packed with extra features. So before you make your choice take a look at some of the most important things to consider.

large fish in aquarium

Why Choose A Digital Aquarium Heater?

The best digital aquarium heaters come with key features which often give them the edge over analog ones. Let’s take a look at some of these below.

Temperature Range And Accuracy

While digital aquarium heaters often have a similar temperature range to analog ones, somewhere in the region of 68 to 94°F, they can be more accurate. Some are accurate to +/- 1°F, but there are others that are even accurate to +/- 0.5°F.

This can be important if you own a nano aquarium, for example, as the temperature can fluctuate more in a smaller volume of water [1]. An accurate digital aquarium heater can help maintain a consistent temperature in your tank.

Water Temperature Control

Digital aquarium heaters are often more accurate when it comes to setting them too. An analog heater may have a dial showing 2 to 5-degree increments, or even just a plus/ minus knob. This can make setting an exact temperature quite difficult.

But digital aquarium heaters tend to allow you to accurately adjust the temperature in 0.5 or 1-degree increments using a digital display. They also often show the current water temperature vs. the set temperature on the same display.

Temperature control is made easier with digital aquarium heaters as in many cases the touch control button is located on the cable outside your tank. This means you can see clearly to make any adjustments without needing to place your hands in the water.

Safety Features

You’ll often find digital aquarium heaters will have similar safety features to analog ones, such as an auto cut-off if the heater is allowed to run dry out of the water. But the best digital aquarium heaters go further.

For example, some digital aquarium heaters have a clear display or alarm that will warn if the temperature is too far outside the set range. Some have a display that changes color if your water is out by 1 or 2 degrees either way.

Others also have dual digital temperature sensors to help with accuracy and ensure your tank won’t overheat, so keeping your fish safe.

And because digital aquarium heaters are made from metals like titanium, they often don’t have the standard plastic or glass heating rod like analog ones. Instead, they have a single molded casing meaning there’s less likelihood of your fish getting exposed to the heating element.

Calibration And Memory

When it comes to initial calibration, digital aquarium heaters can be much easier than analog ones to set up. 

Some analog heaters have a separate calibration dial to the temperature setting dial. To calibrate, you have to use a separate aquarium thermometer to find the temperature of your tank and set the calibration dial. You can then set the desired temperature.

Digital aquarium heaters simplify this process as they show the current water temperature on the display straight away, so all you need to do is set the temperature you want.

And many digital aquarium heaters have a memory function, so if the unit loses power it will remember calibration and temperature settings. So there’s no need to reset everything when you turn it back on.

Types Of Digital Aquarium Heater

Many digital aquarium heaters are fully submersible, making them particularly safe as the heating element is always underwater so less prone to cracking or shattering. But let’s look at the key types of digital aquarium heater below.

Submersible Heaters

The most common type of digital aquarium heaters, as well as analog, are submersible. Digital submersible heaters come in several different designs. 

Some are single units made from metal like titanium that sit submerged under the water. Others consist of a titanium rod that is submerged in the water with the display and control unit sitting outside your tank.

As many digital submersible heaters don’t rely on the design of a heating element inside a glass rod, they come in a wide range of sizes. From micro heaters less than 3 inches long to powerful 800 Watt heaters or larger for 150 gallon tanks and above.

Immersible Heaters

These heaters hang on the back of your aquarium with the heating element submerged below the water line. They are often less efficient than submersibles and are generally only found as part of smaller aquarium starter kits.

Digital immersible heaters are even rarer. Many manufacturers don’t tend to use digital technology when providing these heaters for small aquarium kits. So you’ll struggle to find a wide range of digital immersible heater sizes for various tanks.

Inline Heaters

Although uncommon, you can find inline heaters with digital adjustment and LED displays. Inline heaters sit outside your aquarium and are attached to the outflow from the sump or external filter. They work by heating the filtered water before it returns to your tank.

Digital inline heaters often have two temperature sensors for better accuracy, but they do have to be set up carefully. They can be prone to leaks if the inflow and outflow tubes are not correctly aligned and tightened.

How To Choose The Best Digital Aquarium Heater For Your Tank

Whether you have a freshwater or saltwater aquarium, or a large setup or small nano tank, there are a wide range of digital aquarium heaters to choose from. Here are the main things to think about when finding the best digital aquarium heater for your tank.

small fish in aquarium

Tank Size and Water Type

Analog heaters made for larger tanks, such as 75 gallons, can be physically large in size themselves. For example, some 300 Watt rod-shaped heaters can be around 20 inches long

Digital aquarium heaters, on the other hand, can be powerful and compact. You get compact 500 Watt digital heaters for 100 gallon tanks, for example. But you can also get very small digital heaters of around 3 to 4 inches suitable for nano aquariums.

One of the key things to check when you’re choosing a digital aquarium heater is water type and compatibility. Some of the metals and other materials used in digital aquariums heaters mean, unlike glass analog heaters, they are unsuitable for saltwater tanks as they can corrode.

Wattage vs. Tank Size

Aside from being more compact, and the fact that digital aquarium heaters sometimes heat your water more rapidly, there’s little difference when it comes to power output. You’ll need the same amount of power, measured in Watts (W), as you would with an analog heater.

The general rule is it takes around 2.5 to 5 Watts to heat 1 gallon of water [2]. But as well as the volume of your aquarium, your room temperature, and the temperature you want to maintain your water at also affect the Wattage of heater you’ll need.

We’ve produced a list of recommended Wattages needed to maintain a temperature in your tank of 74 to 80°F, suitable for many tropical freshwater fish. This is based on a room temperature of around 72°F [3]. 

Large Aquarium VolumeTo Maintain Approx. 75 to 80°F
3 US Gallons15 – 25 Watts
5 US Gallons25 – 50 Watts
10 US Gallons50 – 75 Watts
20 US Gallons50 – 75 Watts
40 US Gallons100 – 150 Watts
55 US Gallons150 – 200 Watts
65 US Gallons200 – 300 Watts
75 US Gallons250 – 375 Watts
90 – 100 US Gallons275 – 450 Watts
150 US Gallons450 – 750 Watts

Temperature Readability And Adjustability

Unlike analog heaters, most of the best digital aquarium heaters will have clear LED or LCD screens, often showing the current and set water temperature. This makes reading your heater’s temperature simple, even if you are a few feet from your tank.

Digital aquarium heaters also have precise touch button control allowing you to adjust the temperature in 1 degree or sometimes 0.5-degree increments. Don’t worry too much about the latter though as 1-degree increments are precise enough in most cases.

Digital Thermometer

The best digital aquarium heaters have one or sometimes two digital thermometers built-in. Dual temperature sensors tend to help increase the accuracy and ensure your water is maintained at a stable temperature.

But even digital aquarium heaters can sometimes be out by a degree or so, especially when you first install them in your aquarium. So we always recommend keeping a separate in-tank thermometer in your aquarium for extra peace of mind.

Safety Features

Submersible heaters tend to be the safest type of aquarium heater. As they sit fully below the water line there is less chance of incorrectly positioning them, or leaving part of the heating element exposed, as can happen with immersible heaters.

As most digital aquarium heaters are submersible, either the whole unit or the heating element itself, you generally won’t need to worry. Also, check what protection is around the actual heating element. A bumper guard is essential for keeping your fish coming into contact with it.

Our Verdict

We found the Cobalt Aquatics Neo Therm Pro Heater to be the best digital aquarium heater overall for its high degree of accuracy, compact design, and ability to maintain a stable temperature.

But if you own a saltwater aquarium the Hygger Saltwater Titanium Heater is a great choice with a range of sizes suitable for small and large tanks.

Whichever you choose from the list above, a digital aquarium heater can be an excellent choice if you want an easy-to-control and highly accurate way of maintaining a stable temperature in your aquarium.


We’ve answered some of the most frequently asked questions when it comes to choosing a digital aquarium heater for your tank. Take a look at the answers below.

How Easy Are Digital Aquarium Heaters To Use?

The best digital aquarium heaters are very easy to use. They usually have a digital display and touch button adjustment, so you can easily see the exact temperature you are setting.

How Do I Set Up A Digital Aquarium Heater?

Most digital aquarium heaters come pre-calibrated. As soon as you place them in your tank they’ll show the current water temperature. Simply set your desired temperature and that’s it!

How Do I Know If My Digital Aquarium Heater Is On?

Unlike analog heaters, which sometimes have a small LED heating light, digital aquarium heaters have large LED or LCD screens that clearly shows when they’re actively heating.

Do I Need More Than One Aquarium Heater?

Whilst you can get powerful digital heaters of 800 Watts or more, many aquarists recommend two smaller heaters in an aquarium over 55 gallons as it can help with heat distribution.

Photo of author
Matt Thomas
Matt has been keeping fish since junior high when he used to look after his parent's tank. He loves guppies, cichlids, and his crowntail betta named Bobby.

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