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If you found this article you already know a heater is something you need for your fish tank. You care enough about your finned friends that you want to make sure they get the best aquarium heater available.
There are a wide array of aquarium heater types, sizes, and brands. This article was written to help sort through the noise. I give you the things you need to keep in mind when selecting an aquarium heater as well as my recommendations.
Heaters reviewed in this article include:
- Aqueon Pro Adjustable Aquarium Heater
- Fluval E Advanced Electronic Heater
- Hygger Titanium Aquarium Heater
- Cobalt Aquatics Flat Neo-Therm Heater
- Hydor In-Line External Heater
Why An Aquarium Heater is Important
Why is a good fish tank heater important? If your reading this you already know the answer.
It’s all about the fish!
There are many beautiful tropical fish on the market and they need supplemental heat. The ambient temperature in your room is not warm enough. Unless you are cold-blooded and have your home thermostat set to 80° F!
Correct water temperature is essential to the health, well-being, and survival of your aquarium inhabitants! Not only do you need a heater capable of reaching the correct temperature, you also need one that will consistently and reliable hold that temp. Fish do not handle temperature swings very well.
Types of Aquarium Heaters
Now that you understand the importance of an aquarium heater let’s look at the different types available.
Submersible Aquarium Heater
Let’s start off with the most common type of aquarium heater. The submersible water heater.
A submersible water heater is a watertight tube with an electrical heating element. As the name implies, this type of heater is installed completely under the water in your fish tank. They are usually attached to the glass vertically or diagonally.
The most basic heaters come factory set to a certain temperature. Most of them, however, have an adjustable thermostat. These adjustable heaters have a temperature adjustment dial at the top of the heating element. There will also be an indicator light that lets you know if the heater is off or on.
There are a couple of minor downsides though. First off they can take up room and be a bit of an eyesore in your fish tank. Secondly, they may heat the aquarium water unevenly. This means that the water will be warmer closer to the heater.
Aside from those downsides, submersible aquarium heaters are affordable and reliable. This makes them an easy choice for beginner and intermediate fish keepers.
Non-submersible heaters are an older style heater that hangs on the aquarium frame. The temperature adjustment valve sits above the water line and the heating element sits in the water. These types of heaters have largely been replaced by submersible water heaters.
This type of heater is placed within the filter housing or sump. The water is heated as it passes through and back into the tank. The advantage of this type of setup is that it hides the heater out of sight and heats the water evenly.
This really isn’t a different type of heater but rather just a different way of heating the water. Submersible heaters can be used this way as long as they fit correctly.
Inline Aquarium Heater
An inline aquarium heater is a heating element with a passageway for the water to flow through. This type of filter is plumbed into the filtration system on the outflow side of the filter. It warms up the water leaving the filter before it enters back into the tank.
The advantages to this type of system are the same as with an in filter heater. It is out of view and provides more even heating than a submersible heater. One disadvantage is that if the water flow stops your aquarium also stops getting heat.
It does require a more complex set up. This won’t work with your standard hang on back type aquarium filters. You need an external canister type filter system to use a fish tank heater like this. But, if this is the set up you have or want this is the heater for you.
Substrate Heating Cable
A substrate heating cable uses the electrical cable as a heating element. This is placed in the substrate and the heat cycles through the substrate and into the water.
Substrate aquarium heaters are a very efficient way to heat your fish tank. They also do a good job of heating the water very evenly. This is an ideal heater for planted aquariums as a warm soil bed is more natural. The warm water column that rises out of the substrate aids in nutrient cycling as well.
Unfortunately, this type of water heater isn’t widely used and as such there aren’t very many to be found on the market.
Aquarium Heater Watts
Now that you have an idea of the best aquarium heater type for you, we need to consider the size. More specifically, watts.
A traditional figure has always been 4 watts per gallon or 1 watt per liter. To keep the math simple, that means with a 10-gallon tank you would need at least a 40-watt aquarium heater.
Nowadays some are recommending as low as 1 – 2 watts per gallon or 0.5 – 0.2 watts per liter.
These generalizations do not take into account the ambient room temperature. Is your home thermostat set to 72° or 62° F? This will make a difference in how hard an aquarium heater will have to work to maintain the set temp. The larger the temperature difference between your room and aquarium, the more watts you will need.
Please reference the table below for a good estimate on how many watts you may need.
|Aquarium Heater Size Guide|
|Tank Size||Heater Watts|
|5 Gallon/20 Liter||20|
|10 Gallon/40 Liter||40|
|20 Gallon/75 Liter||80|
|30 Gallon/114 Liter||120|
|40 Gallon/150 Liter||160|
|50 Gallon/200 Liter||200|
|75 Gallon/300 Liter||300|
|100 Gallon/379 Liter||400|
You can always use two heaters to meet your aquarium heating requirements. Just make sure the combined wattage is enough for your set up. This has an added benefit as well. If one heater dies you have the other as backup. This will prevent the water temp from dropping too dramatically.
What is the Best Aquarium Heater?
At this point, you know about the types of heaters and the number of watts needed for your fish tank. So now let’s take a look at the best aquarium heaters available today!
Best Aquarium Heater Reviews
It has a very plain black design that blends in well with the aquarium. Let’s be honest, your aquarium heater isn’t the feature you want to be drawing attention to anyway.
It has an adjustable temp control with a red LED that lights when on. One small downside is that the temp settings on the dial are not entirely accurate. The actual temp seems to be 2 – 4° F lower than set on the dial, but it does hold the temp steady.
I don’t see this as a big downside, however. I always recommend a separate thermometer anyway. I haven’t had a problem getting mine set at the needed water temperature.
I have an Aqueon Pro in one of my personal aquariums and am pleased with it. There are reports from some people about defective units with the newest version. Mine has been running strong for 6 months as of writing this, so I wouldn’t let this concern you.
- Gravity shutoff feature
- Shatterproof plastic construction
- Plain black design blends in well inside aquarium
- Available in 50, 100, 150, 200 and 300 watts
- Some quality control issues
- Temperature control dial not entirely accurate
The first thing that stands out to me with the Fluval E advanced electronic heater is that it is fancy. While the technology hasn’t changed much with most heaters this one has some advancements. So if you are a bit of a tech geek this may be the heater for you.
It has a digital microprocessor and an LCD temp display. The really cool thing about this display is that it changes color in relation to the set temperature. If the water temp is below where you set it, it will turn blue. If it’s at the correct temp it will turn green. And if it’s too warm it will turn red.
There is also a fish guard around the heating element. This is intended to prevent any of your aquarium inhabitants from coming into contact with the heater element. While it functions as intended it may be leading to the main issue with this heater.
This heater has trouble reaching and maintaining the desired temp. This is most likely due to the fish guard which restricts water flow around the heating element. It must be placed in a spot where there is adequate water flow. You may need to get creative with placement. Many people have had success placing it under the water filter outflow or in front of the intake.
I really like this heater for its creative features. I just wish it didn’t have the minor heating issue to deal with.
- Very accurate digital temp display
- The LCD screen turns color in relation to set water temperature
- Fish guard prevents fish coming into contract with heating element
- Available in 100, 200 and 300 watts
- Needs proper water flow to reach and maintain set temperature
Unlike the other aquarium heaters, this one has an external heater controller. This design has a few advantages.
For one, you can make adjustments to the temperature outside of the tank. This means that you won’t have to put your hand in the fish tank to adjust the temperature as you do with most heaters.
I also like the fact that when the heater is off there is no electricity going to my aquarium. Most heaters with built-in thermostats always have residual electricity sitting in the water. There are too many stories of fish being electrocuted or fried! This unit gives me a bit more peace of mind.
Another difference with this heater is the titanium tube that houses the heating element. Other heaters use glass or cheap plastic which can shatter or break. You won’t have to worry about that with this heater.
Overall this seems to be a good quality unit. There are only a couple of minor downsides. The cheap suction cups for the heating element don’t work very well.
The heater also only operates in 1-degree increments. This means the heater won’t turn on until 1 degree under your set temp. No big deal in my opinion.
- External temperature controller
- Titanium heating tube won’t shatter
- Quality construction
- Available in 50, 100, 200 and 500 watts
- More expensive than other options
- Suction cups don’t work very well
The Cobalt Aquatics Flat Neo-Therm Heater is one of the only aquarium heaters not made in China. Produced in Poland this heater has a unique flat design.
The flat design can be quite useful because it can be placed in sumps or water filter chambers. This is useful if you want to give your aquarium a clean look without an unsightly water heater visible.
This heater does a good job of holding a steady temp to within 0.5° F. Just make sure you buy the correct wattage rating for your set up.
Unfortunately, the temperature can only be set in 2-degree increments. You should also check the water temperature with a separate thermometer as the integrated one isn’t always accurate.
There are reports of some quality control issues with this heater. While the majority of them work well some of them fail prematurely. This can result in the death of your fish. A good stand-alone temperature controller can prevent this.
To ensure proper operation and prevent damage to the unit follow the setup instructions precisely. Place it in the water for 15-30 minutes before you turn it on. Immediately turning it on can lead to a host of issues.
- Made in Poland
- Sleek thin design can fit just about anywhere
- Available in 25, 50, 75, 100, 150, 200 and 300 watts
- Reports of quality control issues
- Temp setting only adjusts by 2-degree increments
Last but not least I had to include an option for those of you who like to take their aquarium to the next level. There are many advantages to an external in-line heater and the Hydor is a good example. It is only available in 200 and 300 watt sizes though so it is only compatible with larger aquariums.
Like all in-line heaters, the Hydor provides consistent and even heating. No need to worry about mounting the heater just right in the tank for even heat. Every ounce of water will be the same temperature.
Many people report these heaters lasting 5 years or more. For the occasional unit that does fail prematurely, Hydor has a 2-year manufacturer warranty. Unlike many other aquarium heaters, this one will not get stuck on if it malfunctions and fry your fish. It is designed to turn off when there is a malfunction which is a much better scenario!
One small con with this unit is the fact that the thermostat isn’t always accurate. The temperature setting on the dial doesn’t always correspond to the actual water temp. That is why I always recommend a stand-alone thermometer or temperature controller.
Overall this is a good heater to start with if you are considering an external heater for its many benefits.
- Provides the most even heating possible
- External mounting makes your tank look clean and professional
- Malfunction fail-safe turns heater off so it doesn’t cook your fish
- 2-year manufacturer warranty
- The thermostat isn’t always accurate
- Makes clicking noise when turning off and on
- Some units fail prematurely
And the winner for best aquarium heater is……..
There are a lot of factors to consider when choosing the best water heater for your fish tank. Size, features, quality, and reliability are all important. As a stand-alone unit, the Hygger Titanium Aquarium Heater is the best choice for most people.
This heater is the most reliable among the bunch and that is due to a few different factors. The heater element is encased in a metal tube. This won’t crack or shatter and it comes with an external temperature controller.
If you just need something cheap and reliable I recommend the Aqueon Pro. It’s a basic no-frills heater that does the job.
Aquarium Heater Issues
Unfortunately, aquarium heaters don’t last forever. It is becoming harder and harder to find a quality heater that will last years. When they do die it often results in dead fish. Many cheap units will get stuck on and fry fish. Heater element cases may crack and leak internal materials and electricity into the tank.
Be sure to follow installation instructions correctly. Also, be prepared to check the temperature frequently when the unit is first installed. And last but not least, have a backup plan if your heater fails in any way.
Some of the issues inherent to even the best aquarium heaters can be mitigated by using a quality temperature controller. This is a separate unit that sits outside of the tank and controls the temp. Please see my recommendations for the Best Aquarium Heater Controller.