What Is A Submersible Aquarium Heater?

As its name suggests, this is a device that’s kept submerged in aquarium water to heat it up and maintain comfortable temperature for fish. There are several types of heaters:

  • Hanging/Partially submersible
  • Fully Submersible
  • Substrate
  • In-line
  • Filter

Compare The Best Submersible Aquarium Heaters

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  •  Aquarium capacity: Up to 10 gallons
  • Temperature range: 59 to 94°F
  • Type of installation: Submersible
  • Dimensions, inches: 2.5 x 1.5 x 3.5

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  • Temperature range: 78°F ( + / - 2°)
  • Type of installation: Suction cups
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ViaAqua 200-Watt Quartz Glass Submersible Heater with Built-In Thermostat review
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  • Temperature range: 68 to 93 °F
  • Type of installation: Submersible
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Orlushy Submersible Aquarium Fish Tank Heater review
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  • Temperature range: 68 to 89 °F
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Submersible Aquarium Heaters Reviews

With these reviews, you will be able to select the best aquarium heater that fits your requirements and budget ideally.

Aqueon Submersible Aquarium Heater

Aqueon Submersible Aquarium Heater


Simple and minimalistic, Aqueon heater can be placed in any position (horizontal or vertical). It allows adjusting temperature by 1 degree within the range of 68-88 °F. The model can be used in aquariums up to 20 gallons. Once the required temperature level is set, it shuts off automatically to eliminate the risk of overheating.

Our opinion

A cheap, convenient model, but it can heat one part of aquarium leaving the opposite walls quite cold.


  • Automatic shut-off;
  • Non-expensive;
  • Precise temperature adjustment.


  • Suitable for small aquariums only.
FREESEA 50-300Watt Aquarium Fish Tank Heater

FREESEA 50-300Watt Aquarium Fish Tank Heater with LED Temperature Display


Ideal for small aquariums up to 10 gallons, this fully submersible aquarium heater boasts the temperature range of 59 to 94°F (15 – 34°C). It can maintain the optimal temperature automatically and will stop when the needed level of heat is reached. The temperature is shown on the display, and you can change the settings manually.

Our opinion

Great for replacing other thermometers, should be used in small aquariums.


  • Wide temperature range;
  • Display showing degrees.


  • Relatively expensive.
Aquatop Aquarium Glass Submersible Heater

Aquatop Aquarium Glass Submersible Heater, 300-Watt with Liquid Crystal Vertical Aquarium Thermometer


Another automatic heater, the model from Aquatop has a preset temperature of 78°F ( + / – 2°), so no adjustments are required. It’s produced from durable PPC plastic. The indicator shows when the device is on, and a suction cup allows placing it where you need. Suitable for small aquariums up to 5.5 gallons.

Our opinion

Good option only for small aquariums with tropical fish.


  • Cheap;
  • No manual adjustment required.


  • Only preset temperature;
  • Works only for small aquariums up to 5.5 gals.
ViaAqua 200-Watt Quartz Glass Submersible Heater

ViaAqua 200-Watt Quartz Glass Submersible Heater with Built-In Thermostat


This is the best submersible aquarium heater for larger aquariums (up to 200 gals). You can use the model in both saltwater & fresh aquariums. Made of high-quality quartz glass, it withstands damage and has a temperature range from 68 to 93 °F.

Our opinion

A perfect choice for large aquariums and optimal overall warming.


  • Very powerful;
  • Suitable for large aquariums.


  • No suction cups for attachment.
Orlushy Submersible Aquarium Heater

Orlushy Submersible Aquarium Heater,100W/150W/200W/300W Fish Tank Heater


This 300 Watt heater is made for large aquariums (50-80 gal) and comes with a thermostat to control the temperature ranging from 68 to 89°F. Automatic shut off prevents overheating. It’s equally good for saltwater & freshwater tanks.

Our opinion

Non-expensive but a bulky heater for large aquariums, buy it if you’re ready to deprive your fish of a bit of space.


  • High efficiency;
  • Non-expensive.


  • Takes much space.

Frequently Asked Questions

Q: What Type Of Submersible Heater If My Aquarium Is Not Glass?

A: You don’t want the aquarium to be melted by the hot thermostat, so choose models where the coil is encased in glass. Besides, it’s better to choose models that are supposed to be simply submerged in water and don’t have suction cups or other elements attaching them right to the tank walls. Generally, it’s safe to use aquarium heaters in plastic tanks – it still has a safe temperature.

Q: How To Use Submersible Aquarium Heater?

A: The process is quite simple:

  • Set up the optimal temperature on the thermostat.
  • Place the device in the water and attach it, if necessary.
  • Plug the device in and let it heat up the water.

If it doesn’t have an automatic shut off, you’ll have to watch the temperature of the water and switch the thing off at the right moment.

Q: How Do You Set Submersible Aquarium Heater Temp?

A: It depends on the model. In most of them, it’s done with buttons – follow the applied instruction.

Q: Where To Put Submersible Water Heater In Aquarium?

A: Some of the heaters can be attached to the inner side of aquarium walls with suction cups. Others simply hang on a cord and can be left submerged.

Q: What to do when the aquarium heater broke and how to prevent it from recurring?

A:If your aquarium heater broke, you should throw it away immediately. Don’t try to repair it and use one again, even if seems easy to you. Just to be on the safe side, buy a spare heater: if your old heater breaks, you will be able to replace it quickly. Another precaution measure includes buying a cover for a heater. It will prevent its contact directly with fish and the water in the case of breakage. Finally, it makes sense to follow the manufacturer’s instructions on the heater maintenance and clean it regularly in order to increase its lifespan.

Q: What is the correct way to install an aquarium heater and are they fully submersible?

A: Every aquarium heater type requires a certain method of installation. If you opt for a submersible one, it should be placed low into the water yet not touching the gravel. As gravel won't conduct heat well, once you turn on the heater and it heats the gravel, the tank glass will crack or shatter. Submersible heaters are fully submersible and no part must be left out of the water. If your model has a thermostat, you'd better install the heater horizontally. This way the thermostat will spot the water temperature more accurately to turn the heater on and off when necessary.

Conclusion & Our Recommendations

Hopefully, these submersible aquarium heater reviews will help you make the right decision. For small aquariums, Aqueon Submersible Aquarium Heater is the most cost-efficient choice with a price tag up to $20. For the same price, you can find a model for larger aquariums, for example, Orlushy Submersible Aquarium Heater.

When in search of a heater, look at three key aspects: power consumption, materials, and automatic temperature control. Besides, temperature range also matters. For tropical fish, seek for models with a high heating capacity. For marine fish, choose heaters to keep water at the level of 60 F degrees.

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Perry Coleman

To keep your fish alive and healthy, you need to provide the correct environment for them, including the optimal water temperature. As such, you’ll need a reliable aquarium heater. It’s important to pick out the correct water heater that will adequately heat the water in your tank but not overheat it.

Willie Edwards

Can I use Multiple Heaters for One Tank?

Alisa Mendoza

Yes, you can. If your fish tank is large, one heater can be insufficient for it. Meanwhile, two heaters used simultaneously will do their work perfectly well. Also, two heaters let heat the water more evenly. That is why if you have enough space, it always makes sense to consider using two medium-size heaters placed in the opposite corners of the tank, instead of one big heater.

Bobbie Freeman

A large percentage of fish require warm water to survive, so unless you live in a year-long warm country, the likelihood is, you’ll need a heater to keep your tank at a consistent temperature. Some people choose to keep more than one heater in their aquarium, especially if the aquarium is large and is being kept in a cold room. This is ideal because if the first heater stops working, the second will keep the water at the desired temperature.

Lena Soto

What is the best aquarium heater size to buy for my tank?

Alisa Mendoza

The heater size depends on the aquarium size. Larger tanks require more powerful heaters and vice versa. Approximately, 5 watts are sufficient to heat up one gallon of aquarium water. Thus, a 25-watt heater will do for a 5-gallon tank, while a 20-gallon aquarium needs at least 100 watts.

Herbert Barnett

The Fluval E electronic heater comes with advanced technology that you might find useful in your aquarium. It has an LCD that shows you the temperature in real-time because of the dual temperature sensors. You can preset the desired temperature, and the heater will use its color-coded alert system to notify you if the water temperature drops or rises above 2F from the preset temp.. The fast heat technology help maintain the optimal temperature in the aquarium. It comes with mounting brackets to help you position and secure the heater. The 100watt aquarium heater support up to 30 gall tank.

Lance Peterson

The Aqueon Pro is one of the most versatile aquarium heaters. It comes in five power options, from as little as 50 watts to 300 watts, and responds to the demands of most users. It suits smaller and larger tanks and boasts a wide temperature range that adjusts from 68°F to 88°F.Fully submersible, the heater is also equipped with an electronic thermostat that provides ultra-accurate measurements to plus or minus 1°F. An auto shut-off function keeps your fish safe if the unit overheats and also prolongs the heater’s lifespan.

Chad Cox

Even though in the cold weather, you don’t face the lack of dissolved oxygen in the water like in hot temperature, low temperature is not comfortable for your fish or plants. They endure great stress during such low temperature and death can be seen. So it’s best to do something to cope up with that kind of climate.

Darlene Ellis

Do I Need to Check My Heater Frequently?

Alisa Mendoza

Even though aquarium heaters come with built-in thermostats, it’s recommended to measure the water temperature with an independent thermometer every day. The best approach is to measure it in the opposite corner of the tank, as this helps to make sure the water is mixed properly and heated evenly.

Perry Elliott

With the best aquarium heaters, you should have an easier time handling the heating needs of the aquarium. It would be great to get one with an aquarium heater controller, meaning that you get to easily set the temperature of the heater to work optimally.

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