7 Reliable Heaters Fully Submersible with Thermostat

Try to live in Minnesota or anywhere in Canada without a heating system, and see how that goes.

I’m just trying to point out that you should also use the best aquarium heater you can get for your fish when they need it because the consequences can be fatal.

My recommended heater is the Fluval E, continue reading for more options.

Why Do You Need a Heater?

Types of Heater - Where Should You Place It?

Aquarium Heaters Reviews

So now let’s take a closer look at some of the most popular aquarium heaters you can buy today.


Aquatop Quartz Glass Submersible Heater

This heater measures 14.5 x 1.5 x 1.5 inches, and its power ranges from 50W to 300W.

This gives you a temperature range of 68° to 93° F for up to 75-gallon tanks.

Its warranty is only for a year, although you can check the site’s website if this changes—and it only applies when you buy from an authorized reseller.

It comes with suction cups for the setup, while it also features double insulation with high-quality insulated glass. You just turn a knob to adjust the temperature, and the display tells you the temperature setting.


  • It’s very powerful.
  • It’s easy to set up.
  • Its temperature settings are quite accurate.
  • It’s easy enough to adjust the temperature settings, and the display for the temperature setting is highly visible.
  • It’s quite hardy, with many other people saying that it has worked for them for years.
  • It’s very affordable.


  • Its warranty is only a year. Even though that’s a lot better than some pet stores offer (some of that offer only 15-day warranties) other companies offer a longer time frame.
  • It’s a bit fragile for shipping, with customers reporting that they received shattered heaters.

Jetsu 300W Submersible Glass Heater

This is a fully submersible heater, and its 300W power is enough for a temperature range of 65° to 93° F for tanks ranging from 60 to 75 gallons. Its measurements are 13 x 1.8 x 1.8 inches.

It comes with a 30-day money back guarantee, along with a 1-year warranty.

For the setup, you get 2 suction cups that enable you to mount it horizontally, vertically, or even diagonally.

There’s no temperature display, but there’s a red glow visible when it’s heating the water.


  • It’s very easy to install and use.
  • The Quartz Silica Tube is much more durable than regular glass heaters.
  • Its temperature setting is also very accurate.
  • ​There’s a tube cap at the end so that you don’t accidentally touch the gravel with it.
  • It’s affordable too.


  • There’s no convenient temperature display aside from the knob at the top.

EHEIM Jager Aquarium Thermostat Heater

This fully submersible heater measures 1.4 x 19.9 inches, and it’s recommended that you place it horizontally.

It’s available at different watts, from 25 and 50 watts all the way to 300 watts (there are 9 models available).

The 300 watts can handle as much as 150 gallons, although the recommended ratio is 5 watts per gallon of water.

The 25W is one of the best betta heaters around, as it can heat the water to at least 78° F in small tanks no bigger than 7 gallons.

The warranty is good for 3 years. The setup requires some calibration, however.


  • The TruTemp dial stays within 0.5 of your desired temperature.
  • It turns itself off when the water level goes low (hence the horizontal recommendation).
  • The glass is shatter-proof and shock-resistant.
  • It has a good reputation for durability.
  • You see an indicator light when it’s working.


  • It’s very long, and it may be difficult to set horizontally.

Aqueon Pro Heater

This is also another fully submersible heater that measures 4 x 14 x 2 inches.

It’s available in 5 different watts, and the 250W version can handle raising the temperature 15° F above room temperature in a 90-gallon tank.

It’s easy enough to install, but you’ll need to follow the directions in the setup guide.

The temperature is in Fahrenheit, and you’ll just need to set this horizontally so that you can see the temperature setting. There’s also an indicator light.

As for the warranty, there’s nothing better in the industry as you get a lifetime warrantee.


  • The lifetime warranty is truly excellent.
  • The warranty is also probably redundant, because it’s shatter-proof and virtually indestructible.
  • It contains an electronic thermostat so it’s accurate. These advantages combined have made it one of the top rated aquarium heaters today.


  • The customer service can be hit or miss—some get excellent service, while others not so much.

Fluval E Electronic Heater

The 300W heater is fully submersible, and it can handle 100 gallons with a temperature range of 68° to 93° F.

It’s actually available in 4 versions, with the 50W version good for up to 15 gallons.

It offers a great LCD display of the temperature, and it’s in both °C and °F.

It’s easy enough to set up in various angles, although the manual warns against setting this horizontally.

Just follow the directions, as there are steps involved.

It also comes with a 5-year warranty.


  • It offers accurate temperature settings with its dual temperature sensors. You can actually set the temperature in 0.5 degree increments.
  • It comes with an LCD display.
  • There’s an automatic shutoff feature.
  • The fish guard is integrated, so that your fish doesn’t get in contact with the heating element. It’s even protected against shocks from bigger fish species.


  • Setting it up horizontally may void the warranty.
  • You’ll need to follow the steps in the guide when setting it up.

Finnex Hang-On Electronic Controller (Titanium)

This 500-watt fully submersible heater only measures 14.5 x 1 x 1 inches.

It works very quickly and powerfully, as it’s capable of handling up to 120 gallons. Its temperature range is from 70 to 92° F.

The temperature control is set outside the water, which is nicely convenient.

It offers an accurate temperature setting (within 2 degrees) and there’s a LED heating indicator. It does warn that it should only be in a horizontal position, however.

It’s quite tough too, with its corrosion-resistant titanium tubes. This makes it ideal even for saltwater application. Unfortunately, the warranty situation is a bit on the murky side.


  • It can work very quickly with its 500 watts.
  • The control is outside the water.
  • It doesn’t take up much space in the tank.


  • It may be tough, but that warranty problem can be trouble.

Cobalt Aquatics Neo-Therm Heater

Now this fully submersible heater is small, as it only measures 11 x 1.5 x 0.5 inches.

It may only be 150W (the 300W and 400W are coming soon) but it’s able to set the temperature from 66° to 96° F in a 40-gallon tank.

It has to be placed vertically, or you might void the 3-year warranty.

This offers very accurate temperature readings, with up to 0.5° F accuracy. The LED display even shows the set temp and the tank temp at the same time. It also shuts off automatically before it overheats, and the outer casing is shatterproof.


  • The temperature accuracy and display is terrific.
  • Its durability is fine.
  • It’s also easy to use with its “one touch” control system.


  • The biggest they offer is just 200W, until the more powerful heaters come along.

My Pick

My personal favorite is the Fluval E Electronic Heater.

It comes with heater guards that also protect my fish, and it should be a boon for many beginners as well. They’ve had some quality issues in the past but recent aquarium heater reviews are mostly positive as long as it survives the delivery. The 5-year warranty is nice too, and it’s very easy to use.

All others are OK, especially the Cobalt for smaller aquariums.

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