9 Best Aquarium Heaters: Submersible, Immersible, In-line
Aquariums are usually filled with water at room temperature but some fish, especially the tropical species, thrive well in warm waters. This is where an aquarium heater comes in.
Additionally, the water is not guaranteed to stay at a constant temperature because the heat outside might drop. Just like humans, fish do not like these frequent temperature changes and this further emphasizes the importance of an aquarium heater.
With this in mind, it is vital that you get the best aquarium heater. This article takes a close look at 10 of the best ones in the market so as to help you pick the most suitable one for your fish.
- 9 Best Aquarium Heaters – Reviews
- 1. Fluval A772 – Best Overall Aquarium Heater
- 2. Cobalt Aquatics 31004 – Electronic Aquarium Heater with Thermal Protection
- 3. Aqueon Pro – Shatterproof Aquarium Heater
- 4. Aquatop GH-50W – Fully Submersible Aquarium Heater
- 5. Eheim 3612090 – Aquarium Heater with Re-calibration Settings
- 6. ViaAqua VA 50Q – Aquarium Heater with a Ceramic Core
- 7. Penn Plax CH8100 – Affordable Aquarium Heater
- 8. Lifegard Aquatics Aquarium Heater – Best Aquarium Heater for Large Tanks
- 9. Hydor T08203 – In-Line Aquarium Heater
- How to Buy the Best Aquarium Heaters
- How to Install the Aquarium Heater
9 Best Aquarium Heaters – Reviews
1. Fluval A772 (Best Overall Aquarium Heater)
2. Cobalt Aquatics 31004 (Electronic Aquarium Heater with Thermal Protection)
3. Aqueon Pro (Shatterproof Aquarium Heater)
4. Aquatop GH-50W (Fully Submersible Aquarium Heater)
5. Eheim 3612090 (Aquarium Heater with Re-calibration Settings)
6. ViaAqua VA 50Q (Aquarium Heater with a Ceramic Core)
7. Penn Plax CH8100 (Affordable Aquarium Heater)
8. Lifegard Aquatics Aquarium Heater (Best Aquarium Heater for Large Tanks)
9. Hydor T08203 (In-Line Aquarium Heater)
1. Fluval A772
(Best Overall Aquarium Heater)
2. Cobalt Aquatics 31004
(Electronic Aquarium Heater with Thermal Protection)
3. Aqueon Pro
(Shatterproof Aquarium Heater)
4. Aquatop GH-50W
(Fully Submersible Aquarium Heater)
5. Eheim 3612090
(Aquarium Heater with Re-calibration Settings)
6. ViaAqua VA 50Q
(Aquarium Heater with a Ceramic Core)
7. Penn Plax CH8100
(Affordable Aquarium Heater)
8. Lifegard Aquatics Aquarium Heater
(Best Aquarium Heater for Large Tanks)
9. Hydor T08203
(In-Line Aquarium Heater)
1. Fluval A772 – Best Overall Aquarium Heater
- Power: 100 Watts
- Ideal tank size: Up to 30 gallons
Fluval is one of the best aquarium heater brands in the market and this particular model does not disappoint. Although a bit expensive, the product has a very impressive array of features.
For starters, it has an LCD screen that displays the set water temperature in both degrees Celsius and Fahrenheit. This makes it very easy to adjust because the results are displayed digitally on-screen.
Additionally, it has an easy-to-use adjustment lever for setting the temperature, and it does so in 0.5ºF increments or decrements.
The screen itself is also a safety feature because it lights up in green when the water is at the set temperature, blue when it is more than 2ºF below and red when it exceeds by more than 2ºF. This makes it the most reliable aquarium heater.
Dual temperature sensors make this possible by sensing the current water temperature in real time and displaying the results on the screen using those colors.
For safety, the heater has a fish guard, which is basically a protection layer that keeps the animals inside the aquarium from coming into direct contact with the heater core. This also protects the core from external shocks caused by large fish collisions.
On the downside, this unit does not have a dry run protection feature and thus, might get destroyed when left on in an empty tank.
2. Cobalt Aquatics 31004 – Electronic Aquarium Heater with Thermal Protection
- Power: 100 Watts
- Ideal tank size: 29 gallons
Cobalt Aquatics’ 31004 features a fully electronic thermometer and thermostat, which are computer tested and proven to maintain the accurate temperature to + or – 0.5ºF.
The whole system is guarded by a built-in thermal protection circuitry, which powers off the heater once it starts to overheat. This ensures you do not boil your fish and plants.
Additionally, this system includes an LED light that displays both the set temperature and the current tank temperature to enable you to monitor the temperature changes easily without using an external thermometer.
The product’s temperature settings range from 66ºF - 96ºF, and this basically covers all the required temperatures for most fish. As a result, the Neo-Therm is ideal for freshwater, saltwater, reef and terrarium tanks, which makes it a very versatile tool.
Other than that, the heater is fully submersible aquarium and has a thin profile (1/3 inch thick), which gives it a very modern look. This thin body is made from shatterproof material, making it virtually indestructible.
Other features include a reversible vertical mounting bracket with a suction cup and an easy to set, 1-touch system. The only problem is its high cost.
3. Aqueon Pro – Shatterproof Aquarium Heater
- Power: 50 Watts
- Ideal tank size: 10 gallons
This Aqueon Pro heater has a high-quality shell, which is shatterproof, non-corrosive and gives an even heat distribution across its length.
For temperature settings, the unit features a pointed control knob that can be used to adjust the heat to any value between 68ºF to 88ºF. Although this range is not as big as that of the Neo-Therm above, it still gives you some room to play with.
A built-in thermostat ensures that temperatures are kept steady and is accurate to + or – 1ºF. In case this fails, an auto shut-off mechanism kicks to ensure that you don’t kill your fish and resets once the water has cooled down.
LED lighting is used to indicate whether the heater is heating or not. It lights red when heating and green when not heating, and this makes it possible to monitor the unit from outside because this can also show you whether the unit is still functioning or not.
If the 50-watt model is too small for your tank, there are larger 100-watt model. However, despite the power size, all of them are fully submersible and can be positioned either vertically or horizontally.
4. Aquatop GH-50W – Fully Submersible Aquarium Heater
- Power: 50 Watts
- Ideal tank size: Up to 13 gallons
Similar to the Aqueon Pro above, this Aquatop heater is fully submersible and includes suction cups to hold it in place in an upright vertical position inside the tank.
Inside, the heater has analog temperature settings and incorporates the use a knob to adjust to a higher or a lower temperature. However, it does not have a numbered rim around the knob to show the temperature figures.
Instead, the actual temperature readings are shown on the side of the heater tube using both Celsius and Fahrenheit scales. These run from 20ºC to 34ºC and 68ºF to 93ºF respectively.
Construction wise, the unit is made of a double glass layer, which makes it a bit delicate but provides very good insulation to the electrical components inside while also giving even heat distribution.
5. Eheim 3612090 – Aquarium Heater with Re-calibration Settings
- Power: 50 Watts
- Ideal tank size: Up to 16 gallons
Instead of having a knob, this heater incorporates the use of a dial to select the desired temperature and has a readjustment ring that allows you to recalibrate the unit to + or - 8ºF for more accurate reading.
This recalibration ensures that the heater is set correctly so that the temperature set using the dial is the actual temperature that it achieves in the tank water. The result of this is a very accurate thermostat that does not cause under or overheating.
For safety, Eheim Jager’s unit features thermo safety control that shuts off the heater once it is pulled out of the water and turns it back on when reinserted into the water. This prevents dry running, which would otherwise ruin the heater’s coil.
Structurally, the product is made using lab-grade shatterproof glass that is quite strong and resistant to harmful chemical and biological substances as well as extreme temperature fluctuations. This makes it very durable.
Additionally, glass gives an even heat distribution by enlarging the heating surface when the unit is fully submerged in the water.
6. ViaAqua VA 50Q – Aquarium Heater with a Ceramic Core
- Power: 50 Watts
- Ideal tank size: Up to 13 gallons
ViaAqua’s aquarium heater is characterized by a ceramic core, which is covered by a quartz glass casing. This improves on heat distribution but must be handled with care due to the delicate glass cover.
That said, you get highly visible temperature settings on the side, which are displayed in both degrees Celsius and Fahrenheit. These range from 20ºC to 34ºC and 68ºF to 93ºF on the respective scales.
Temperature adjustment is done via a knob on the upper part, which turns on either a plus or minus direction visibly on the scales. This makes it very easy to use.
Other features include a relatively low price tag, a small size (measuring 1.1 × 1.1 × 8.2 inches) and a lightweight design that weighs only 6.9 ounces.
7. Penn Plax CH8100 – Affordable Aquarium Heater
- Power: 100 Watts
- Ideal tank size: Up to 20 gallons
Penn Plax is also a well-known brand in the aquarium accessories segment and made this affordable unit to be the best budget aquarium heater in this review. However, this does not mean that it lacks in terms of features.
For starters, the heater is fully submersible, with the option of placing it either horizontally or vertically inside the tank. It has a glass casing that covers the heating element on the bottom end to provide an even heat distribution.
The unit comes preset at a temperature of 76ºF, but this can be easily changed using an adjustment knob on the upper part.
Manual knob adjustments are usually a little bit less accurate and this is can be seen on its 1ºF accuracy rate. However, its dual scale (Celsius and Fahrenheit) makes it easy to adjust because the readings are clearly visible on the side of the heater tube.
8. Lifegard Aquatics Aquarium Heater – Best Aquarium Heater for Large Tanks
- Power: 300 Watts
- Ideal tank size: 110 – 150 gallons
Lifegard Aquatics’ aquarium heater is a top-rated aquarium heater and this is primarily because of its high power size (300 watts), which makes it ideal for large 110 – 150-gallon aquariums.
This means that the unit is compatible most saltwater fish tanks because these are usually large in size so as to cushion the fish from various water quality fluctuations that might occur from time to time.
Functionally, the unit is submersible and has a temperature adjustment range of between 68 and 88ºF. Thermal protection keeps it in check just in case the temperatures exceed the set value, saving your fish from life-threatening temperatures.
To give you further trust in this product, the company made sure that the heater is UL certified, which means that it meets all the specific defined requirements of an aquarium heater.
Structurally, a huge chunk of the tube is covered with quartz glass, which is reinforced using a bi-metal construction, making it very strong and durable.
9. Hydor T08203 – In-Line Aquarium Heater
- Power: 300 Watts
- Ideal tank size: 53 – 80 gallons
Unlike the products above, Hydor’s T08203 is an in-line aquarium heater that does not occupy space inside the tank. However, it must be connected to the return line of an external canister filter or sump.
It is important to note that the filter used must be functioning properly so as not to cause clogging inside the heater.
All of them are quite pricey but they have a high precision electronic temperature control feature that guarantees safety against the risk of overheating.
How to Buy the Best Aquarium Heaters
1. Type of Aquarium Heater
There are various types of aquarium heaters. These are:
Submersible heaters: Submersible heaters such as Aquatop's GH-50W are very efficient at heating because their entire bodies are placed inside the water. This means that all the heat produced goes directly into the water without any losses.
However, if they are too big, they might occupy the space that is meant for the fish. As such, the best submersible heater should be small in size.
Immersible heaters: These are quite similar to submersible heaters except for the fact that not all the unit’s body is sunk in the water. The heater should be hung on the aquarium wall so that only the heating element can submerge into the water.
Such a setup means that the aquarium top cover needs to have an allowance for the upper part of the heater.
An important thing to note here is that immersible heaters are not ideal for saltwater aquariums because the salt might corrode the electrical circuitry if the water splashes inside.
However, the major disadvantage with these heaters is that they can electrocute the fish. If not properly secured, the heater may fall inside and short because the circuitry is not waterproofed.
In line heaters: With Hydor's T08203 as the ideal example, these external heaters must be connected to the return pipe of either a canister filter or a sump.
They are good options for larger tanks with larger fish because, with them, there is no contact between the heater and the fish. As such, the fish cannot break them as a result of high impact collisions.
However, they are harder to maintain because clogging may occur, especially if the filter is not functioning properly.
In sump heaters: These are usually much larger the in-line pumps but basically, work in the same way as them.
Substrate heaters: This type consists of a heating element buried under the gravel, from which the heat radiates to the rest of the tank. The problem with this type is that it is very difficult to set up.
Buying Advice: if you have a small fish tank, say up to 50 gallons in capacity, a submersible heater such as Cobalt Aquatics' 31004 is the best option. For bigger tanks, an in-line heater like Hydor's T08203 is your best bet.
The power factor goes hand-in-hand with the tank size. For a 100-watt heater that is suitable for a 30-gallon tank (like Fluval's A772), this would be the same as buying two 50-watt heaters, each suitable for a 15-gallon tank.
Therefore, when buying any heater, it is important to compare the power and tank size in this manner before settling down on one.
3. Tank Size
Tank size is usually considered due to compatibility issues. You cannot buy a 50-gallon tank heater if you have a 20-gallon tank. Similarly, you cannot buy a 15-gallon tank heater if you have a 40-gallon tank.
However, for larger tanks, it is recommended to buy multiple small heaters as compared to a single large one because of two reasons.
One, multiple heaters will distribute heat more evenly around the tank as compared to one unit and two, in case one fails, the rest will at least maintain the water at a good temperature for the fish.
4. Adjustable Temperature
This aspect is usually considered in terms of the range of adjustable temperature. The bigger the range, the better the unit because it gives you more room to play with.
This is because it enables you to provide a much higher or a much lower temperature environment for the fish, depending on their preference.
5. Ease of Maintenance
At some point, you will have to clean the heater. Submersible and immersible units are usually very easy to clean, especially if they have glass insulations. All you have to do is wipe them clean. Check out ViaAqua's VA 50Q.
In line and in sump heaters are a bit more complex to clean because you might be forced to disassemble the kit so as to wash it from the inside.
6. Additional Features
The most important additional feature that an aquarium heater should have is a thermal protection feature. This shuts down the unit automatically when the thermostat fails so as to prevent continuous heating to the point of boiling the fish alive.
For this, most highly advanced heaters such as Lifegard Aquatics' Aquarium Heater contain this feature.
How to Install the Aquarium Heater
Since submersible aquarium heaters are the most common options, we will use them as an example. They are installed using the following steps:
1. Inspect the heater before installation to ensure that it has no damages or defects
2. Identify the best location to fit the heater in your aquarium. This should be close to the return pipe from the filter in order to utilize that current to spread the heat.
3. Clean the glass surface on the identified area and attach the suction cups that come with the heater.
4. Adjust the heater temperature then install it inside the tank using the attached suction cups.
5. Let it rest for about 5 minutes so that the casing can adjust to the water temperature. This is important because sudden temperature spikes might cause cracks, especially in glass.
6. Place an external thermometer on the opposite side of the heater, if the heater does not have a built-in thermometer.
7. Turn on the heater and let it operate for about a day without the fish inside the tank. During this time, keep monitoring the thermometer in order to check whether the water temperature is maintained at the set temperature. Reset and recalibrate if needed.
8. If all is well, add the fish to the tank and continue monitoring throughout.
1. Is the aquarium heater really necessary?
This depends on the type of fish that you want to keep. If you intend to keep tropical fish and you live in an area where the room temperature is very cold, it is necessary to have an aquarium heater.
However, if you want to keep temperate fish, these can survive well in temperatures that range from 18 - 22ºC, meaning that they can survive in room temperature. In such a case, aquarium heaters are not necessary.
2. Where should I place the aquarium heater?
For a submersible aquarium heater, the best area to place it is across or near the water flow channels. This is close to the inlet or outlet to the filter.
At this position, the flowing water will greatly help distribute the heat throughout the entire tank.
3. How much electricity does the aquarium heater use?
This generally depends on two things: the size of your tank and the temperature adjustment.
As a reference point, a heater heating a 30-gallon tank to 72ºF consumes about 110 kWh. The same tank heated to 82ºF requires 440 kWh.
There is no exact calculation to answer this question but the estimates above might help you determine how much electricity an aquarium heater consumes.
4. Is the aquarium heater easy to clean? And how often to clean?
This depends on the type. Submersible and immersible are usually very easy to clean because you only need to wipe them.
In line and in sump heaters are harder to clean since the heated water channels are hidden inside the unit, meaning that some disassembly might be necessary to access these parts.
Cleaning should be done as you clean or change the tank water so that everything that goes back inside is fresh.
5. Can I put a heater in a plastic fish tank?
Yes, you can. Aquarium heaters are not meant to boil the water and thus, the little warming effect that they have on the water will not affect acrylic tanks.
6. How many watts does my aquarium need?
This mostly depends on the temperature increase that you want as well as the size of your tank. A guide to help you with this is shown below.
They might look small but by going through this aquarium heater review, it is clear that there is a lot of information about these gadgets that must be understood before making any purchase.
That said, we highly recommend Fluval's A772 as the overall best aquarium heater because it hosts a lot of high tech features such as a color-coded temperature display and dual sensors for high accuracy.
- Aquarium Heater Size guide - The SprucePets