6 Popular Heaters for Small Tanks. Pros and Cons

6 Popular Heaters for Small Tanks

Aquarium heaters are equipment used to keep the aquarium at the right temperature in order to make it safe and comfortable for the fauna living within.

Unlike larger tanks, small tanks can be quite challenging to heat precisely due to their relatively small sizes and the lesser volume of water they hold. Also, if there are temperature fluctuations in the place you live, it can be a good idea to have a heater.

In addition, fish, shrimp, crayfish, crabs, frogs, etc. are poikilothermic animals meaning that they are incapable of maintaining a relatively constant core temperature. This implies that their body temperature varies according to the temperature of the surrounding medium.

Aquarium heaters are therefore necessary to help maintain an optimal/ideal water temperature in the tank. It is a good investment that will help safeguard the lives of your aquarium fish and other lifeforms in your tank especially during winter when the ambient room temperature falls considerably.

On average, the temperature of a freshwater tank should be set at about 68 – 82 °F (20 – 27 °C); however, this is not absolute because the temperature needs of animals vary from species to species.

Keep reading for a detailed review of the best heaters for small tanks (10 gallons/40 L or lesser).

Types of Heaters

There are several types of heaters available for a variety of tanks. Knowledge of this subject matter is particularly important if you aim to provide the best heater for your small fish or shrimp tank.

1. In-line Heaters

These heaters are designed to be mounted outside the tank.

In-line heaters are connected by a tube line; which can be connected to a filtration system. Nonetheless, they can be installed with only a pump without a filtration system.

The main advantage of this type of heater is its ability to maintain a constant temperature throughout the aquarium.

2. In-tank Heaters

This category contains aquarium heaters that can be placed inside the aquarium.

Without a doubt, in-tank heaters are the most common type of aquarium heaters. These include immersible, submersible and substrate/pad heaters.

2.1. Immersible Heaters

These kinds of heaters are commonly known as hanging heaters.

Immersible heaters are most suitable for 10 gallons (40 L) tanks. If a tank is smaller than 10 gallons, this heater may not be a good fit.

Although they function similarly to submersible heaters — keep in mind that immersible heaters are however less effective than submersible heaters and they cannot be fully submerged underwater.

2.2. Submersible Aquarium Heaters

Submersible heaters are typically placed completely under the water.

They are compact and do not take up much space in the tank. And there’s no need to employ an exterior room while making use of the kind of aquarium heater.

Submersible heaters have several low wattage ranges for small tanks. For aquariums of 5 to 10 gallons, it is appropriate to consider heaters with an output of 50 watts. Whereas for aquariums with volume ranging from 2 to 5 gallons, you should consider a 25 watt heater.

2.3. Substrate or Pad Heaters

Substrate or pad heaters may be submerged in water or placed under the aquarium gravel.

A good example of pad heaters is the Hydor Slim Heater for small aquariums. This product can increase the aquarium water temperature by 5 to 10 °F. It comes in 3 models (7.5 watts, 4 watts and 15 watts), crafted in round or oval-shaped pads for tanks up to 5 gallons.

Substrate or pad heaters can be used in glass or acrylic aquariums with ease.

Heaters for Small Tanks

This is my list in order of priority.

6) Marina Betta Submersible Aquarium Heater

6 Popular Heaters for Small Tanks - Marina Betta Submersible Aquarium HeaterThis submersible aquarium heater has several amazing features.

Its exterior is quite resilient and made of fine-quality polymer. It has suction cups which are ideal for easy placement and support. In addition, Marina Betta aquarium heater has a simple design that makes it fit ideally with other components in the tank.

If you would like to save energy, then this model is your best bet as it is an 8 watt aquarium heater.

The heater was specifically designed to maintain warm temperatures for bowls and tanks that hold not more than 1.5 gallons of water.

Let’s have a look at some pros and cons of this small tank heater.

Marina Betta aquarium heater

  • Made of fine quality polymer
  • Has an indicator light
  • Has suction cups for easy attachment
  • Heats the tank up to 75 – 85 °F or 24 – 30 C (depending on the tank size)
  • Efficient and energy conservative

  • Ideal for kits less than 2 gallons (<1 L)
  • Lacks an on/off switch
  • Low precision
  • Non-adjustable temperature control (no thermostat inside)

5) Aqueon Mini Aquarium Heater

6 Popular Heaters for Small Tanks - Aqueon Mini Aquarium HeaterThe Aqueon Mini Aquarium Heater is an energy-conserving and efficient 15 watt heater for small tanks between 4 – 10 gallons (20 – 40 liters).

Note: If you need a heater for a smaller tank, there are mini heater for 5-gallon tank and less (link to Amazon).

Irrespective of the low wattage, its operation is not underwhelming. This heater is efficient and maintains a constant temperature even in pico tanks.

Also, the aquarium heater is fully submersible and it has a shatterproof casing which makes it nearly indestructible according to the manufacturer’s claims.

Aqueon Mini Aquarium Heater

  • The Aqueon mini aquarium heater possesses suction cups that makes placement easy
  • Durable and efficient. It is built with a safe and highly durable material that promotes longevity
  • Easy temperature regulation
  • Safety shutoff
  • Price

  • Low accuracy and precision
  • The heater would need to be reset or recalibrated after a while to ensure maximal functionality
  • The preset heater

Aqueon Mini Aquarium Heater – (link to check the price on Amazon)

4) Fluval Submersible Glass Aquarium Heater

6 Popular Heaters for Small Tanks - Fluval Submersible Glass Aquarium HeaterThe Fluval Submersible Glass Aquarium Heater is another popular heater for small fish or shrimp tanks.

This is a sleek and sophisticated heater with an amazing built-in reflective technology that blends in with its surroundings, and it works great to provide high quality heating to a variety of tanks — even those with a volume less than 10 or 15 gallons.

Also, Fluval Aquarium Heater is made from high-quality material and it comes with a three-year warranty.

Fluval Submersible Glass Aquarium Heater

  • Has the ability to withstand impact due to its shock-resistant Borosilicate glass
  • High density ceramic heat sink
  • Easy-to-adjust temperature control dial
  • Has a computer-calibrated thermostat
  • Ideal for saltwater and freshwater tanks
  • Comes with a three-year warranty
  • Price

  • Requires the water level to be observed and maintained constantly (to avoid heating from dry running)
  • Low accuracy and precision (complains about overheating)
  • Computer-calibrated thermostat often fails
  • The preset heater

Fluval Submersible Glass Aquarium Heater up to 15 Gallons – (link to check the price on Amazon)

3) FREESEA Small Tank Heater

6 Popular Heaters for Small Tanks - FREESEA Small Tank HeaterThis aquarium heater is a superior, adjustable model with a built-in thermometer. The temperature can be set between 59 – 94 °F (15 – 34 °C).

The heater has five different models based on wattage.

For small aquariums ten gallons and above, it can be serviced by heaters above 50 watts. Aquarium less than 5 gallons goes well with the 25 watt model. Also, it is made of shatterproof glass making it less indestructible.

Other significant features include a double insulated heater and a temperature dial right at the top of the heater — this automatically switches on or off so it can remain at the ideal temperature. The heater can be placed in any position in the tank, either horizontally, vertically, or diagonally.

FREESEA Small Tank Heater

  • Fully submersible
  • Very durable due to its shatterproof casing
  • Automatic switch
  • Adjustable thermostat
  • Easy to read thermometer (LED) for swift temperature monitoring
  • Easy positioning (installing)
  • Compact
  • Can be used in saltwater and freshwater tanks

  • Requires the water level to be observed and maintained constantly (to avoid heating from dry running)
  • The glowing LED setpoint display can’t be dimmed or turned off.
  • Requires additional safety measures. There are reports animals of being stuck in between the plastic covering of the heater (the suction cup area)
  • Short cord
  • Comes in a lot of configurations and that can be a bit confusing
  • Short Warranty (12 months)

FREESEA Small Tank Heater – (link to check the price on Amazon)

2) Cobalt Aquatics Neo-Therm Heater

6 Popular Heaters for Small Tanks - Cobalt Aquatics Neo-Therm HeaterThe Neo-Therm aquarium heater can help maintain optimal aquarium water temperature.

It has a one-touch control system that allows the temperature to be adjusted more easily than many other aquarium heaters.

It also has a built-in thermal protection feature that prompts the heater to shutdown before it gets overheated.

Cobalt Aquatics Neo-Therm Heater

  • The heater can maintain temperatures from 66 up to 96 °F (18 – 35 °C)
  • It has a flat, sleek design
  • Very durable
  • Digital display
  • Very high accuracy and precision(plus/minus range of .5 degrees)
  • Increased thermal regulation and protection
  • Comes with a three-year warranty
  • Lots of variants (up to 6 gallons/24L, 12 gallons/48L, etc.)

  • More expensive compared to competitor brands
  • Risk of failing increases after the first year
  • Overheating when failing (When they fail, they often fail hot) 

Cobalt Aquatics Neo-Therm Heater – (link to check the price on Amazon)

1) Eheim Jager Thermostat Aquarium Heater

6 Popular Heaters for Small Tanks - Eheim Jager Thermostat Aquarium Heater 25wThe Eheim Jager Aquarium Heater is a worthy ultra-modern aquarium heater for freshwater and saltwater tanks.

This product comes available in different models with varied wattages like 25 watts, 50 watts, and 300 watts. The 25 watt model is ideal for 5-7 gallon tanks (20 – 30 liters) whereas the 50 watt model is suited for 7 – 16 gallon or 30 – 50 liters.

This heater has a precise temperature adjustment from 64 – 93 °F (18 up to 34 °C). It help will regulate and maintain the ideal temperature for any animals you keep in the tank.

It is fitted with a true-temp dial that quickly recalibrates the heater for precise temperature regulation, alongside an auto switch, indicator light, and shatterproof glass for extra protection.

Eheim Jager Aquarium Heater

  • Fully submersible
  • Auto switch
  • On/off indicator light
  • High precision and accuracy (plus/minus range of .5 degrees)
  • True-temp dial for easy recalibration
  • Thermo Safety Control (automatic dry run shut-off)
  • Double suction cups and mounting bracket
  • Long cable (1.7 m or 5.6 ft.)
  • Shock-resistant and shatterproof glass
  • Suitable for freshwater and saltwater tanks
  • 3-year warranty

  • Requires regular recalibration to maintain accuracy
  • Size (a little over 9″ (24 cm) for 25 watt and 50 watt models). It can be too big to stand up right.

Eheim Jager Aquarium Thermostat – (link to check the price on Amazon)

Choosing the Heater. Tips

  1. Important: Unlike filters, you have to choose only the heater appropriate for your tank size. If the heater is larger than what your tank actually requires, it may lead to overheating and ultimately – the death of all animals.
  2. My recommendation. Whenever you have a choice – use only adjustable heaters. The main problem with preset heaters is that if they are not heating to the proper temperature, then there’s usually no way of adjusting them.
  3. Use thermometer. Even if the company advertises that you do not need a thermometer – don’t believe them. This is absolutely false. They just want the product to look good in your eyes.

Install the heater on one end of the tank and place a thermometer on the other end. That way, the readings obtained at any given time will serve as a true representation of the aquarium’s temperature condition.

  1. Replacements. Heaters are the most hazardous device in the aquarium hobby. 

You can hear lots of horror stories about heaters malfunctioning and frying everything in the tank. Well, it is true. Even the higher quality manufacturers of aquarium supplies cannot guarantee 100% safety.

Unfortunately, lots of aquarists experience inconsistent heating even with expensive heaters. Therefore, be ready to replace it at any moment if something goes wrong.

Main Features to Look Out For In an Aquarium Heater

  • Adjustable thermostat
  • Auto switch off for thermal safety
  • Shatterproof housing
  • A long power cord to avoid using an extension cord
  • Indicator light
  • Superior quality
  • Mounting bracket or suction cups for placement and stability
  • Temperature calibration
  • Ability to be kept in different positions either vertically, diagonally, or horizontally

In Conclusion

Aquarium heaters are indispensable to fish keepers and aquarists in general since it prevents the water temperature in an aquarium from dropping below the ideal levels.

Animals like fishes, shrimp, frogs, etc. are cold-blooded and they tend to take on the temperature of their immediate environment; hence the need for an aquarium heater. This piece of equipment is tasked with regulating and maintaining a stable temperature for aquarium fish and other critters to grow and thrive in the tank.

Keep in mind that heaters are specially crafted for different aquarium sizes. Therefore, a heater designed for a large tank may not suit a small tank and vice versa.

While shopping for an aquarium heater, make sure to let the vendor know of your tank’s size and the features you desire. Last but not the least, opt for a heater from a reputable brand — preferably, one that comes with a warranty.

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One thought on “6 Popular Heaters for Small Tanks. Pros and Cons

  1. The Marina Betta Submersible Aquarium Heater has been quite efficient in maintaining a stable temperature. The suction cups make it easy to install, and its energy-saving feature is definitely a plus. However, it’s essential to note that it’s best suited for tanks less than 2 gallons. I’ve found it to be a reliable option for my smaller setups, but the lack of an on/off switch and non-adjustable temperature control can be a drawback if you’re looking for more precision, say to adjust the temperature for breeding.
    Thanks for sharing this review!

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