- The Best Aquarium Heater
- 1. Tetra HT Submersible Aquarium Heater
- 2. Orlushy Submersible Aquarium Heater
- 3. Fluval E Electronic Heater
- 4. FREESEA Aquarium Heater
- 5. Marina Betta Submersible Heater for Aquarium
- 6. hygger Titanium Tube Aquarium Heater
- 7. Finnex Hang-On Aquarium Heater
- 8. ViaAqua Quartz Glass Submersible Heater
- 9. Cobalt Aquatics Flat Neo-Therm Heater
- 10. ISTA External Aquarium Heater
Home aquariums look stunning and settling back to watch the aquatic inhabitants is a relaxing way to chill out and unwind. But with so many types of fish, from freshwater to tropical, you need to create and maintain the right environment. As fish cannot regulate their own body temperature, this includes keeping the aquarium water at the right constant temperature to keep them alive.
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Fish tank water heater units come in a range of designs and the type you choose will depend on the size of your aquarium and the marine life you are planning to keep. We dip into some of best aquarium heaters currently on the market so you can choose the right one for your fishy friends.
The Best Aquarium Heater
1. Tetra HT Submersible Aquarium Heater
Automatically adjusts heat output
Heating indicator lights
Can be set vertically or horizontally
Electrical short shut off
Used alone for smaller tanks or in a pair for tanks above 10 gallons, the Tetra HT is a well-priced product that scoops top spot in our best aquarium heaters guide. As a 50W, fully submersible heater, it’s easy to use and can be installed either vertically or horizontally. It also has a built-in thermostat, set to 78°F so you can be sure the water is the right temperature for your fish, without having to re-set to ensure the tank is in the ‘safe zone’. Add in an indicator light, so you know at a glance whether it’s heating or maintaining the water temperature and this is a low-maintenance aquarium heater that can easily be concealed although it does need to be used in conjunction with a tank hood or lid.
2. Orlushy Submersible Aquarium Heater
300W fully submersible heater
Ideal for 50-80 gallon tanks
Adjustable temperature dial
Heat indicator and auto shut off
Coming in at 300W, this submersible heater from Orlushy is suitable for tanks up to 80 gallons and is fully adjustable thanks to the temperature dial which covers 68 to 89°F temperature range. Safe for both saltwater and freshwater , the unit is also fully submersible, with the temperature control hanging over the side. The thermostat is housed in 2mm thickened quartz glass for safety and works to maintain a constant temperature, including an auto shut off when the desired temperature is reached. The heater itself is sleek and modern and you also get a 6ft power cord to give you flexibility as to where your aquarium is located.
3. Fluval E Electronic Heater
Precision digital aquarium heater
Can be adjusted in 0.5° increments
For both salt and freshwater use
Safety features include a fish guard
For use in freshwater or saltwater aquariums up to 100 gallons, the 300W Fluval is a high-tech heater that gives you precise control over the temperature inside your tank. This digital aquarium heater can be adjusted to within 0.5° increments and will continually monitor and display the water temperature via its easy to read LCD display. The temperature range is impressive too – 68-93°F – and with fast heat technology and safety shut off as well as a built-in fish guard, you can be sure your fish are safe and happy. Easy to fit, we also like the included bracket, which means you can position the heater inside the tank at any angle for the perfect view of the display.
4. FREESEA Aquarium Heater
Designed for 1-10 gallon tanks
59 to 94°F temperature range
External adjustable control button
Auto temperature function
The 50W Freesea is ideal for smaller tanks as it is neat and easy to use. The heater has a built-in thermometer and simply needs to be hung over the side of the tank until it is fully submerged. Once under the water, the temperature reading is continually displayed, thanks to the large LED display. Outside of the tank you have your small control panel, with touch button control to adjust the temperature. With a range of 59 to 94°F, this is a versatile little heater too. Add in an auto constant temperature function, which will stop when it reaches the desired temperature and kick back in when the water starts to cool, and you have a smart little heater for your one to 10-gallon aquarium.
5. Marina Betta Submersible Heater for Aquarium
Automatic 8W submersible heater
For smaller tanks up to 1.5 gallons
Durable polymer outer case
Easy to install and use
Betta fish are one of the most popular for home fish tanks but as they are notoriously territorial, are often better kept solo. Which means their aquariums tend to be on the smaller side, which makes these submersible heaters a great value choice. Designed for tanks up to 1.5 gallons, this 8-watt heater is going to keep your betta happy. The design is simple and that’s its beauty – simply stick to the inside of the tank and let it heat up the water to the set temperature. The red indicator light lets you know when it’s heating and the whole unit is made from tough polymer for a long-lasting mini aquarium heater.
6. hygger Titanium Tube Aquarium Heater
100W heating element
Made from durable titanium
Corrosion and shatter-proof
For 10-25 gallon tanks
Shatterproof, this fresh or saltwater heater from Hygger features a corrosion-resistant titanium body for extra strength, safety and durability. Sized for tanks between 10 and 25 gallons, the 100W heater has a built-in thermometer and is easy to mount but must be submerged horizontally next to the filter. Setting and managing the Hygger is slick, thanks to the external control panel which features a dual LCD display that can be set to either Celsius or Fahrenheit. You also get a wide temperature range, from 32 to 104°F with an accuracy of +/- 0.5° C. Add in an auto shut off when it the required temperature and you have a high-performing aquarium heater for your money.
7. Finnex Hang-On Aquarium Heater
150W – ideal for 30 to 60-gallon tank
Maintains temperature within +/-2ºF
External precision control
This hang-on immersible heater is made from titanium to prevent corrosion and will bring your aquarium up to temperature in speedy time. And once there, it works to maintain the water temperature to within +/-2ºF. A good choice for both salt and freshwater, the 150W Finnex is sized for tanks between 30 and 60 gallons. And the slim heating element means it’s pretty easy to hide. You then simply hang the attached control panel – which comes complete with LED indicator, so you know when it is heating – over the side.
8. ViaAqua Quartz Glass Submersible Heater
300W heater with quartz outer
Ceramic core for heat distribution
Adjustable dial and built-in thermometer
For use in fresh or saltwater
With the heating element encased in break-resistant quartz, this fish tank heater is both neat and durable and is a good choice for either fresh or saltwater aquariums. The ViaAqua needs to be fully under the water but the slimline design means it doesn’t take up too much space. And with 300W of heating power, is good enough to be used in larger tanks. The temperature gauge is built in and easily visible under water and the temp adjustment dial is situated on the top for easy access. The ceramic core of the heater is a nice touch as it helps with the even distribution of heat and you also get a red indicator light, so you know exactly when it is working.
9. Cobalt Aquatics Flat Neo-Therm Heater
100W – for tanks up to 29 gallons
66ºF to 96ºF temperature range
LED one-touch display
Our premium pick is this well-designed Neo-Therm Heater from Cobalt Aquatics, which offers energy efficient heating of tanks up to 29 gallons. The flat design works well inside the aquarium and it’s fully submersible for maximum impact. With its reversible bracket it can face inward or outward, depending on your tank set up and is one of the most accurate heaters in our review. With a thermostat accurate to within +0.5°F, it also has a set temperature range of 66ºF to 96ºF so ideal for most fresh and saltwater aquariums. You also get a one-touch system to control the heat, with both the set temp and the current water temperature clearly displayed. Add in the safety of a shutdown system and you have a heater that deserves its premium title.
10. ISTA External Aquarium Heater
External 500W heater
Two temperature sensors
Thermal glass for faster heating
LED dual temperature control
Unlike the other heaters in our review, the ISTA is an in-line external heater which sits inside the filter or sump and doesn’t take up any space inside the tank. The heating power is 500W so a good consideration for larger aquariums and can be used with either salt and freshwater. This heater also has two temperature sensors to check the water as it goes through the inlet and outlet for a more consistent temperature throughout. The thermal glass design also heats up the water faster and the temperature is clearly displayed on the external control. Shown in Celsius, you get both the set temperature and the temperature in real time, so you always know what is happening inside your aquarium.
Best Aquarium Heater Buying Guide & FAQ
Why You Need an Aquarium Heater for Your Tank
For your fish to survive, you need to replicate their natural aquatic environment and the key is getting the water temperature just right. While many cold-water fish can survive in room temperature water, so you are unlikely to need a heater as long as the water temperature remains constant, tropical fish need to have warmer water. And this is why you need an aquarium heater to provide the optimum living conditions. A consistent water temperature is also essential to reduce environmental stress, and a fish tank heater with a thermostat will be able to continually regulate to ensure the water is always within the recommended range.
Things to Consider When Choosing a Tank Heater
There are several key factors to consider when picking the right aquarium heater:
The type of aquarium – the heater you choose needs to be suitable to the tank you have as well as the marine life you are keeping. Warm water fish need to have a constant temperature, while cold water fish need their environment to be cooler and based on the room temperature. Always check the model of heater to ensure it's compatible with your aquarium tank and its occupants.
Tank size – the larger your tank, the more you need to ensure you are heating it consistently and it may mean you need to install two smaller heaters rather than a single unit. The manufacturers of your aquarium heater should indicate its capacity and type/size of tank it's best for. How powerful the heater is will also depend on the tank size and how long it will take to bring the water up to and maintain the desired temperature.
Aesthetics - as well as the enjoyment of caring for your fish, your aquarium is to be looked at and so the style of the heater can be an important consideration. Some heaters are unassuming and small, so less noticeable while others are designed to be hidden. Submersible heaters are the most visible while in-line or filter heaters can be discretely positioned on the outside of your tank.
Easy to maintain – while aquariums can be beautiful to look at, they do need regular cleaning and maintenance to keep your fish in tip-top health. To make your life easier, look for a tank heater that's durable and simple to remove and clean.
Types of Aquarium Water Heaters
There are three main types of aquarium heaters to choose from, with different designs and benefits:
Submersibles sit fully under the water and will typically keep your tank at a more consistent temperature than other types. A fully submersible heater has a coiled element inside a glass, titanium or toughened plastic tube and should be placed inside the tank next to the filter inlet, so it heats the water as it comes back into the tank.
Also known as a hanging heater, the immersible heater fits over the top of the tank, with the heating element hanging down to sit in the water and heat it up. This type of fish tank heater are a popular choice for beginner freshwater tanks but need a hole in the tank hood to be fitted correctly. Less efficient than submersible heaters, immersibles are not recommended for saltwater tanks.
An in-line heater sits inside the sump or filter to that it can heat up the water as it comes back into the aquarium. Made from heat-resistant plastics, in-line heaters are a good choice for tanks with larger or more aggressive fish, or with marine life that has a habit of attacking tank equipment. However, they can be expensive.
How to Install an Aquarium Heater
Most of today’s aquarium heaters have been designed to be easy to install. Always read the manufacturer’s instructions for your particular fish tank heater but as a guide:
- Before installing, check the heater is intact and has no damage or exposed wires
- Ensure the aquarium is empty of fish or marine life
- Decide on the location you want to install the heater and ensure the glass surface is clean
- Fit the heater as per the manufacturer’s instructions, ensuring it's clear of any marine plants or aquarium decorations
- Leave the heater to rest without turning it on for around 30 minutes so that the casing can adjust to the water temperature
- Using a thermometer, take a reading of the water’s temperature then turn on the heater and adjust the temperature to the required level
- Leave the heater on for 24 hours before checking the water temperature then check every four or so hours, adjusting the settings until the desired set temperature is reached and maintained
- Once you are happy that the current temperature is constant, return your fish to their aquarium and let them settle.
Our Top Pick
For price, ease of use and performance, the Tetra HT Submersible Aquarium Heater scoops our best choice pick. Ideal for aquariums up to 10 gallons, they can be doubled up for larger tanks and are fully submersible. With a built-in thermometer, there's no need for constant adjusting as the heater is set to the optimum temperature control for your fish and will continually maintain that heat. Add in a heat indicator light, auto-shut off and easy set up, and you have a smart all-round heater for the home aquarist.
Q: What size aquarium heater do I need?
The size of aquarium heaters is measured in watts to indicate the amount of power – and heat – they can generate. Various factors will help you to determine the right size of heater for your aquarium, including how big or small the tank is and how many gallons of water it holds. You also need to factor in the average air temperature of the room your aquarium is in – the colder the room temperature, the bigger the difference between that and the required water temperature for your fish, so the larger the heater you'll need.
Q: How many watts does a tank heater use per gallon?
Experts recommend five watts of heat for every gallon of water, but this depends on whether you need to heat the water up to 10 degrees above the room temperature and that you are using a tank lid to retain the heat and prevent cooling by evaporation. If you live in a particularly cold location, you could need more than five watts per gallon to get the tank water up to the required temperature for your tropical fish collection. If in any doubt, chat with your aquarium pet store for advice.
Q: What is the ideal temperature for fish tanks?
It all depends on the type of fish species in your aquarium. Cold water fish are usually happy at room temperature (meaning you may not actually need a heater), whereas tropical fish need to have the heat in their tank carefully regulated, depending on their type and needs. As a general guide, most tropical fish tanks need to have a water temperature of between 25 to 27 degree Celsius.
Q: How long should I keep my aquarium heater on?
You can actually leave the aquarium heater on 24/7 as they should have an internal thermostat that will turn off the heat once it reaches a set or specific temperature, keeping the water temperature constant and appropriate for your fish inhabitants. When buying a new aquarium heater, ensure that it has a thermostat and it can be programmed to the temperature you require.
Q: Can fish burn themselves on the heater?
While aquarium water heater burns on aquarium fish are pretty rare, it is possible for it to happen. Burns can occasionally occur if the fish gets trapped between the fish tank wall and the heater or when a slow moving or sedentary fish rests against the heater, but these incidents can be prevented by the use of a heater guard or choosing an inline or external aquarium heater.