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The Best Saltwater Aquarium Heater For Fish Only & Reef Tanks

Along with salinity, maintaining a stable temperature is key for marine life. So read on if you want to find the best saltwater aquarium heater for your tank!

By Julie Millis
Last updated on

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best saltwater aquarium heater

Marine fish, particularly corals, can be highly sensitive to even small fluctuations and changes in temperature. So whether you own a fish-only or a full reef tank, finding the best saltwater aquarium heater is key.

Within the team, we’ve owned several saltwater tanks over the years and so we set about finding the best saltwater heater available today.

Overall we chose the Hygger Saltwater Titanium Heater for its consistent and accurate heating at an affordable price.

But there are many different saltwater setups, from small pico and nano tanks right up to large aquariums with complex coral displays. So we’ve included heaters from some of the best brands to cover all these scenarios.

Let’s take a look at the list!

  1. Best Overall: Hygger Saltwater Titanium Heater
  2. Best For Accuracy & Alerting: Fluval Electronic Heater
  3. Best Budget Pick: Eheim Jager Aquarium Heater
  4. Best For External Or Sump: Hydor ETH Inline Heater
  5. Best For Pico & Nano Reef Tanks: Cobalt Aquatics Flat Neo-Therm

Best Saltwater Aquarium Heater Picks Reviewed

All the heaters below have been assessed against key criteria for saltwater use. These include material and anti-corrosion properties, accuracy and temperature stability, ease of use, and safety features.

1. Hygger Saltwater Titanium Heater


  • Heater Type: Submersible, adjustable, digital
  • 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: Overall

Hygger’s Saltwater Titanium Heater is made from anti-corrosive titanium and is specifically designed for marine tanks with high salinity. It comes in a range of sizes from 50 to 500 Watts, so you can use it with a 10 gallon nano reef tank or a large 120 gallon aquarium.

It’s adjustable from 32 to 104°F and highly accurate (to +/- 0.5°F). So it’s ideal if you own a reef tank with sensitive corals needing a specific temperature. And as the controller sits outside the tank you can adjust it without getting your hands wet.

Unlike many heaters, the Hygger has its thermostat built into a separate temperature probe rather than the heating rod. So you can position the probe and heating element at opposite ends of your tank for more accurate heating.

With a 1-year warranty for peace of mind from faults, the Hygger gets good feedback from owners for its accuracy, durability, and ease of use.

  • Anti-corrosive titanium for saltwater tanks
  • LED controller with easy-to-read current and set temperature
  • Separate temperature probe for accuracy
  • Accurate to +/- 0.5°F
  • 1-year warranty
  • Not suitable for acrylic aquariums
  • Heater guard not included

2. Fluval Electronic Heater


  • Heater Type: Submersible, adjustable, digital
  • 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, fish bumper guard
  • Best For: Accuracy & Alerting

Although not the most expensive on our list, the Fluval Electronic Heater is one of the most accurate thanks to its dual temperature sensors. This along with an adjustable range of 68 to 93°F, which can be set in 1°F increments, make it perfect for sensitive marine life.

E Series heaters come in a range of wattages, from 100 to 300 Watts, making them suitable whether you have a 30 gallon or a 100 gallon tank. And the integrated bumper guard runs the full length of the heater. So your fish are fully protected from the heating element.

The LCD screen is clear to read and set and has the VueTech color alert system. The screen shows green when your tank is at the set temperature, but blue if it’s under by 2°F or red if over 2°F too high. So it’s easy to see any issues and correct them.

Calibration is easy. Simply place the heater in your tank and it will detect and display the current temperature – all you need to do is set the desired value. Overall many owners praise the E Series for being accurate and maintaining a consistent temperature.

  • Accurate dual temperature sensors, can be set in 1°F increments
  • Color alerting to show if temperature is out by +/- 2°F
  • Integrated fish bumper guard
  • 5-year warranty
  • Can be difficult to position during setup

3. Eheim Jager Aquarium Heater


  • Heater Type: Submersible, adjustable
  • Dimensions (inches): 25W = 9.5 (length), 50W = 9.6 (l), 75W = 10.2 (l), 125W = 12.2 (l), 150W = 13.6 (l), 200W = 16.0 (l), 250W = 17.7 (l), 300W = 20.0 (l), all 1.4 (diameter)
  • Wattage: 25W, 50W, 75W, 125W, 150W, 200W, 250W, 300W 
  • Key Features: Temperature range of 65 to 93°F, built-in thermostat, heating indicator light, thermo safety cut-off to protect from running dry, recalibration dial for temperature adjustment, shock-resistant shatterproof glass
  • Best For: Budget Pick

The Eheim Jager is one of the most accurate analog heaters available thanks to its TruTemp calibration dial. You simply set the red calibration dial to your tank’s current temperature and the blue dial to your desired temperature.

Manually calibrating the heater in this way makes the Jager much more accurate. So it’s fantastic for saltwater tanks where you need a precise temperature. And yet it’s cheaper than most digital aquarium heaters, so great if you’re on a budget.

Jager heaters come in a range of wattages from 25W up to 300W, making them suitable for 5 gallon up to around 100 gallon fish tanks. But bear in mind while these heaters are slim at 1.4 inches in diameter, they are quite long. So check your measurements if you have a small tank.

This heater has a run-dry sensor which cuts the power if the water level is too low. So you won’t have any issues if it’s accidentally run out of water during maintenance. But as there’s no overheat sensor we recommend keeping a separate thermometer in your tank too.

Overall the Jager provides very consistent heating, as reported by many owners, making it ideal for your saltwater tank. This along with its reliability and affordability make it an excellent option.

  • Affordable price
  • Consistent and accurate heating
  • Run-dry sensor cuts power when out of the water
  • 3-year warranty
  • Manual calibration can be tricky to get used to
  • No overheat sensor
  • Quite a long heater, especially for smaller tanks

4. Hydor ETH Inline Heater


  • Heater Type: External inline, adjustable
  • Dimensions: 12.5 (l) x 4.0 (d) x 4.0 (w) inches
  • Hose Sizes: ½ inch, ⅝ inch
  • Wattage: 200 W, 300 W
  • Key Features: Temperature range of 65 to 93°F, built-in thermostat, electronic temperature dial, LED heating indicator, hanging eyelet
  • Best For: External Or Sump

If you own a larger saltwater tank of 40 gallons or above with a canister filter or sump, the external Hydor ETH Inline Heater is a fantastic option. An external heater is perfect for reef tanks as less equipment inside means the focus can be on your fish and coral displays.

The Hydor can take slightly longer than a submersible heater to reach initial temperature, but once there it does an excellent job of maintaining it. And with an adjustable range of 65 to 93°F and the ability to set it in 1°F increments, it’s ideal for sensitive marine life.

This heater offers excellent protection against overheating with its PTC (Positive Thermal Coefficient) polymer design. PTC becomes non-conductive once it reaches its maximum temperature so the heater automatically cuts off, protecting your fish.

The 200 Watt model, comes with ½ inch or ⅝ inch hose connectors, and the 300 Watt has ⅝ inch connectors. So whether you are connecting to your sump’s pump or canister filter they should fit well.

Inline heaters usually need to be positioned vertically to prevent any bubbles or dry areas from forming inside which can cause cracks. The Hydor comes with a hanging eyelet so you can set it up without having to worry about this.

  • Consistent and even heating for larger tanks
  • Automatic cut-off to prevent overheating
  • Heating indicator light
  • Easy-to-use temperature dial in 1°F increments
  • Takes longer than a submersible to reach initial temperature
  • Can leak during setup, so ensure a good seal with hoses

5. Cobalt Aquatics Flat Neo-Therm


  • Heater Type: Submersible, adjustable, digital
  • 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: Pico & Nano Reef Tanks

The Neo-Therm from Cobalt Aquatics is available in a range of sizes from 25 to 200 Watts. At just 6.75 inches long and about ¼ inch thick at its narrowest point, the 25 or 50 Watt models are great for a 5 gallon pico tank or a nano tank with a small sump compartment.

While the Neo-Therm attracts a premium price the build quality is excellent, with a durable shatterproof plastic casing. So you won’t have any issues with cracks or breakages during maintenance.

It’s also highly accurate to within +/- 0.5 degrees and has a range of 68 to 94°F. So it’s one of the best heaters for maintaining a precise temperature for your marine fish and corals. And the LED lights show the current and set temperature, making it easy to monitor your tank.

Neo-Therm heaters are incredibly easy to use with their One-Touch control button. Simply place in your water, set your desired temperature, and the heater will self-calibrate. But note that adjustment is in 2°F increments.

Although this heater is more expensive than most it receives great reviews from owners for its ability to maintain a stable temperature and ease of use.

  • Flat, compact design
  • Accurate and stable temperature
  • Easy to use One-Touch control
  • Automated overheat shut-off
  • Limited 3-year warranty
  • Quite expensive
  • Can only be adjusted in 2°F increments

Factors To Consider When Finding The Best Saltwater Aquarium Heater

Before choosing the right heater for your saltwater or reef tank, take a look at some of the most important factors to consider.

Clownfish in saltwater aquarium

Why You Need A Heater In Your Saltwater Tank

Marine fish and invertebrates typically need a slightly higher temperature than most freshwater tropical fish. Many reef-building corals, for example, thrive between about 73 to 84°F depending on the species [1].

Choose the right temperature within this range based on researching the type of corals and marine fish you want to keep. And critically, make sure you keep your tank within around 1°F of this temperature rather than allowing it to fluctuate within the range.

Along with salinity, a consistent temperature is one of the key parameters to keep stable in a saltwater aquarium. Variations of even a few degrees can stress your fish and corals leading to disease. The right saltwater aquarium heater is key to managing this.

What Type Is The Best Saltwater Aquarium Heater?

Depending on the size of your tank and whether or not you use a sump, there are two main types of heaters suitable for your saltwater aquarium.

Submersible Aquarium Heaters

Available as analog or digital aquarium heaters, this type is one of the best saltwater aquarium heater choices. Submersible heaters are positioned below the water line and are highly efficient at sensing temperature fluctuations and maintaining consistency.

These heaters are available in a wide range of sizes and wattages. So you can find a suitable submersible heater for a small pico or nano reef tank, or for a large saltwater aquarium of 100 gallons or more.

Inline Aquarium Heaters

Saltwater aquariums are often set up to focus on features like live rock or coral, sometimes with fewer plants than freshwater tanks. An inline aquarium heater is a great option if you want to minimize the equipment on display as it sits outside your tank.

Sitting on the outflow from your external filter or sump, these heaters are very efficient at providing even heating. With wattages starting at around 200W, most are designed for larger tanks around 40 gallons or upwards.

In-Sump Heaters

A sump is commonly used for larger saltwater aquariums of at least 40 gallons or above. This is a smaller external tank positioned underneath the main aquarium housing the filtration and heating equipment.

Like an inline heater, using a submersible heater in your sump will provide your tank with evenly heated water while leaving more room for your fish and corals. Just make sure when choosing the wattage you account for your sump’s size as well as the main tank.

Materials: Glass vs. Titanium Heaters

Many analog heaters tend to have a tough glass casing surrounding the heating coil. These glass heaters are an efficient and cheaper choice for your saltwater aquarium, but they do have the drawback that they can sometimes shatter.

To prevent this, choose one that’s made from a shatterproof material like quartz or borosilicate glass. This will make them less likely to break if accidentally knocked. For example, during a water change.

Titanium heaters often consist of a titanium heating element submerged in your tank with the controller outside on the cable. This makes it easy to adjust the temperature, and titanium is non-corrosive and won’t shatter so is ideal for large saltwater tanks.

Adding Fail-Safes To Your Heater Setup

Having your saltwater aquarium heater fail, either by overheating or failing to switch on, can be devastating to your marine life. So as well as looking for safety features on the heater itself, you can build extra fail-safes into your setup.

Should You Use Two Heaters In Your Saltwater Aquarium?

Whilst not essential, using multiple heaters can be an excellent fail-safe. Having a heater at either end of a large saltwater tank not only helps heat the water more evenly, but it means you have redundancy built in if one fails.

You’ll normally only need this if your tank is around 40 gallons or above. If you do choose to use two, ensure the total wattage of both heaters is suitable. So a 50 gallon tank should have two 125 Watt heaters adding up to a maximum of 250 Watts.

Should You Use A Temperature Controller?

For additional protection, an aquarium temperature controller will regulate your saltwater tank by switching your heater on or off as required. They often come with 1 or 2 additional temperature probes making monitoring your tank even more accurate.

Some temperature controllers can even be connected to wi-fi and alert you to any fluctuations in your tank via text message or smartphone app!

Yellow watchman goby in marine aquarium

How To Choose The Best Saltwater Aquarium Heater

Now take a look at the key features to watch for when choosing the best saltwater aquarium heater for your tank.

Saltwater Aquarium Size vs. Heater Wattage

The power your saltwater aquarium heater needs, measured in Watts (W), is dependent not only on the size of your tank, but also on its turnover rate, and your ambient room temperature.

But as a general guide, to maintain your tank at around 75 to 80°F at a room temperature of 72°F it takes 2.5 to 5 Watts to heat 1 gallon of water [2]. So taking the highest end of this range a 50 gallon tank would need a 250 Watt heater.

It’s recommended to choose the higher wattage as the additional power will allow your heater to cope with colder periods, such as during the winter months. And as long as your heater has a built-in thermostat it won’t overheat your tank once set.

Temperature Control And Calibration

Accurate temperature control is particularly important in your saltwater aquarium. Some damselfish, for example, are sensitive to even slight temperature changes [3]. So look for an adjustable rather than preset heater to give you full control.

Analog heaters can be adjustable to within 1°F, and some have a calibration dial so that you can account for your current water temperature and make them more accurate. But digital aquarium heaters tend to be even more precise, with some accurate to +/- 0.5°F.

Safety And Other Features

Submersible heaters are one of the safest in-tank types. As they are fully submerged below the water line there is less chance of incorrectly positioning them as there can be with immersible ones.

Some heaters have safety features including run-dry and overheat cut-offs, to stop them running out of water or raising the temperature too high. But as a minimum, check your heater is shatterproof and has an indicator light showing when it’s heating.

If you decide to choose an external inline heater, an auto cut-off to stop the heater if the flow from your filter fails is key. Some also have automatic shut-offs to stop them from overheating your water too.

Efficiency And Price

External inline filters can be very efficient for heating a large saltwater aquarium evenly. But in many cases, the best saltwater aquarium heater will be a submersible one, particularly for smaller tanks.

You’ll find the price will vary depending on the wattage, and whether your chosen heater is analog or digital. For example, a 200W analog heater for a 40 gallon aquarium can cost around $40, but the equivalent digital heater can be $60 to $70.

Our Verdict

Whether you own a fish-only or full reef tank with corals, keeping the temperature stable and consistent is key for your marine life.

Overall we chose the Hygger Saltwater Titanium Heater as the best saltwater aquarium heater for its accuracy and stability at an affordable price. 

Or for larger tanks, the external Hydor ETH Inline Heater means you’ll have less equipment on display so you can focus on your fish.

But whichever you choose, use our guide above to select the correct Wattage for your tank and check your measurements to ensure it will properly fit.


Take a look at the answers to the most frequently asked questions when it comes to choosing the best saltwater aquarium heater.

What’s The Best Temperature For A Saltwater Reef Tank?

A reef tank with corals will do best between 73 to 84°F. While the exact temperature depends on the species, many prefer the higher end of this range at about 79°F.

What Is The Best Saltwater Aquarium Heater?

A digital heater made of anti-corrosive titanium such as the Hygger Saltwater Titanium Heater is one of the best aquarium heaters for saltwater tanks.

How Can I Ensure The Accuracy Of My Saltwater Aquarium Heater?

If your heater has a calibration dial set it to your tank’s current temperature to increase the accuracy. Digital heaters can generally be placed in the water and will self-calibrate.

How Often Should I Replace My Saltwater Aquarium Heater?

A good-quality heater should last at least 2 years, and some come with long warranties. But it’s a good idea to budget for a replacement yearly in case of problems.

Photo of author
Julie Millis
Julie has been involved in aquatics for over 15 years. She is passionate about freshwater and saltwater tanks. Julie loves helping with all your fish-keeping questions!

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