Submersible Heaters: Which Is The Best Aquarium Heater?

Before setting up a fish tank, you’ll want to buy the best aquarium heater you can find. A fish tank heater is an essential piece of equipment to keep your fish healthy and thriving. 

Are you not sure where to start? There are so many types of heaters and brands to choose from, and the choices can be intimidating. 

To narrow down your options, I’ve created a list of the five best aquarium heaters on the market today. Whether your aquarium is big or small, these fish tank heaters are here to help. 

Why Do You Need An Aquarium Heater?

Maintaining a warm and stable fish tank temperature is essential to the health of your tropical fish. So, if you plan to keep a tropical fish tank, then a good heater is a necessary piece of equipment to have before adding your fish to the tank. 

Your tropical fish tank temperature should generally sit between 75-80°F (25-27°C). Tropical fish do best at these temperatures and will stay happier and healthier. 

Aqueon explains why it’s bad for a tropical fish’s health to live in water too cold: 

“Fish are cold-blooded – aka ectothermic or poikilothermic – animals, meaning they cannot control their body temperature. Instead, they rely on the temperature of their environment to regulate their metabolisms and activity levels. When it’s too cold, they’re less active, their appetite is reduced and their immune systems are compromised, making them more susceptible to disease.” 

Why Are Submersible Heaters So Popular?

Submersible water heaters are suitable for people who don’t like to see their heaters. Because the entire heater can go in the water, they are easy to hide behind decorations. Submersible heaters are often more efficient and less likely to experience damage. 

5 Best Aquarium Heaters

What makes these aquarium heaters the best? To pick the best heaters, I studied reviews from actual users and compared heating capacity, cost, and durability. 

1. Finnex HMS Digital Titanium Aquarium Heater — Best Aquarium Heater Overall 

For the best of the best, I recommend choosing the Finnex HMS Digital Titanium Aquarium Heater. The Finnex HMS is the best fish tank heater because it has the most features, durability, and versatility. 

The Finnex HMS has the best heating capacity, with 50W options for smaller and 500W for larger tanks. 

With advanced digital controls, the Finnex HMS reads temperature instantly with an accuracy of 0.5°F. The digital controls outside the tank make for quick and easy temperature adjustments. 

PROS: 

• 3-Digit Display & Control 
• 1/10th Degree Calibration Capable Heater 
• Unbreakable Titanium Tube 
• Corrosion-Resistant

CONS: 

• Short Cables 
• Temperature Sensor is Large 

The Finnex HMS has the most advanced technology and safety features, making it the best heater overall. 

5 of the Overall Best Submersible Aquarium Heaters

2. Aquatop Submersible Heater — Best Aquarium Heater For Mini Tanks (Under 10 Gallons)

The Aquatop submersible water heater is the best for mini aquariums under 10 gallons. 

The Aquatop submersible fish tank water heater has the heating capacity to heat up to 13 gallons, far more than the other heaters made for mini aquariums.

It is a small fish tank heater, but it’s adjustable, affordable, and durable. 

PROS: 

• Safe for Freshwater & Saltwater Use
• Easy Installation with Suction Cups 
• Visible & Adjustable Temperature Settings
• Double Insulation & Insulated Glass

CONS: 

• Finicky Temperature Adjustment Knob 
• Larger Size 

5 of the Best Submersible Aquarium Heaters For Mini Aquariums

3. Fluval M-Series Submersible Heater — Best Aquarium Heater For Small Tanks (Under 55 Gallons)

The Fluval M-Series submersible heater is an excellent choice for small aquariums under 55 gallons. These heaters come with a durable shock-resistant borosilicate glass design that reflects light and blends in with its surroundings. 

PROS: 

• Built-In Reflective Technology
• Computer-Calibrated Thermostat
• Easy-to-Adjust Temperature Control 
• Shock-Resistant Borosilicate Glass 
• Suitable for Freshwater & Saltwater

CONS: 

• Larger Size
• No Plastic Guard at the Bottom For Protection

5 of the Best Submersible Aquarium Heaters For Small Aquariums (<55 Gallons)

4. Marineland Precision Submersible Heater — Best Aquarium Heater For Large Tanks (Over 55 Gallons)

The Marineland Precision submersible heater is the best fish tank heater for larger aquariums over 55 gallons. The heater offers several heating capacities from 250W to 400W. 

The temperature adjustment knob is easy to manipulate and understand as the device clicks every time you adjust it up or down by 1°F. The temperature display glows red for easy viewing and temperature reading. 

These heaters are durable, with mica cores surrounded by a flattened mesh heating element for extra protection and heat transference. 

PROS: 

• Suitable for Both Freshwater & Saltwater 
• Easy Temperature Adjustment 
• Durable & Efficient Heating Design
• Safety Switch to Prevent Overheating
• Easy-to-Use Mounting Brackets & Suction Cups

CONS: 

• Larger Size 
• Temperature Reading Light is Very Bright at Night 
• Temperature Numbers on Heater Sit at Random Intervals

5 of the Best Submersible Aquarium Heaters For Large Aquariums (>55 Gallons)

5. Fluval M-Series Submersible Heater — Best Aquarium Heater For Those On A Budget 

The Fluval M-Series submersible aquarium water heater is the best choice if you’re looking for an aquarium heater on a budget. They offer a variety of heating capacities from 50W for the smallest tanks to 300W for larger tanks, and all heater sizes are affordable.  

PROS: 

• Built-In Reflective Technology
• Computer-Calibrated Thermostat
• Easy-to-Adjust Temperature Control 
• Shock-Resistant Borosilicate Glass 
• Suitable for Freshwater & Saltwater

CONS: 

• Larger Size
• No Plastic Guard at the Bottom For Protection

The 2 Best Aquarium Heaters For Those On A Budget

Are Aquarium Heaters Dangerous? 

There isn’t much to worry about when it comes to aquarium heater safety. Aquarium heaters come with safety in mind; you can leave them on 24/7. Most modern heaters include safety features, including “automatic shut-off” to prevent the heater from overheating. 

Just because aquarium heaters and other aquarium equipment are designed to be safe doesn’t mean you can be careless with your equipment. Aquariums are a common cause of house fires. However, aquarium heaters aren’t the cause; power strips are the culprit. 

FOX43 News explains how aquariums cause fires when you misuse them: 

“Detective Hopple showed FOX43 Reveals how a tank full of water can be a serious fire hazard if you do not have what is known as a “drip loop.” The “drip loop” is the part of the power supply cord below the level of the wall electrical outlet. He said aquariums should never be plugged into a power strip that is lying flat on the floor.

“Where they plug into the wall, they should always have a drip loop,” explained Det. Hopple. “The drip loop basically is so that if water does come down, it can’t travel back up and it plugs into the wall. That way, if any water would get on there, it would drop onto the floor and not get into the electrical outlet.”

When water does get into the outlet, it causes corrosion, resistance, and overheating.”

Conclusion 

Consider the Finnex HMS Digital Titanium Aquarium Heater if you’re looking for the best tank heater for your fish. The Finnex HMS heater is one of the best and safest on the market, with the most comprehensive capabilities and the latest technology. 

Prefer one of the other heaters on this list? That’s okay, too. These are the best aquarium heaters whether you have a small or large tank, are on a budget, or want the best heater money can buy. Rest assured that your fish will be warm and safe, whichever heater you choose.  

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About Kaylee Keech

Kaylee has a large goldfish tank filled with feeders she 'rescued' from her old job at the pet store. She also has two small, freshwater community tanks. Her favorite fish became the seahorse after she cared for one during her marine biology course. It's one of her dreams to set up a seahorse tank in her home.