300 Watt Aquarium Heater – Reviews and Buyer’s Guide 2020

Indeed, aquatic beings from the tropical and sub-tropical waters need a stable temperature. The 300 Watt aquarium heater provides a safe heating option for the aquarium, maintaining a constant temperature that is necessary.

Here, you will see different products under 300W aquarium heater category. Likewise, you will be able to analyze the specifications of these products. Moreover, it will give you information about important factors to consider before purchasing an aquarium heater.

300 Watt Aquarium Heater

300 Watt Aquarium Heater

Usually, marine life keepers face a problem in choosing the right heater for their aquarium. But don’t worry, because here you will get many ideas to avoid this issue. As a rule of thumb, the size of the tank and the volume of water it holds help in determining the right aquarium heater.

As a general rule, consider up to 5 watts for one gallon of actual water. Sometimes, you can also use one or multiple heaters in an aquarium to get the desired temperature. Furthermore, the direction of water supply is also an important variable to consider before buying a tank heater.

Without much delay, below are the reviews of some of the best 300w aquarium heaters. Perhaps, these might be the answers to whatever you were looking for in aquarium heater. Not to forget, they are high in quality as well as very affordableble.

Aquarium Heaters RATING PRICE
Cobalt Aquatics Flat Neo-Therm Heater (Sleek Design) ⭐⭐⭐⭐⭐ Check Price
Ehm Heater Jager 300W (Equal Heat Emission) ⭐⭐⭐⭐⭐ Check Price
Uniclife 300 W Submersible Aquarium ⭐⭐⭐ Check Price
VIVOSUN 300W Aquarium Heater ⭐⭐⭐⭐ Check Price
MQ Submersible Aquarium Heater ⭐⭐⭐⭐ Check Price
Kinbo 300 Watt Fish Tank Aquarium Heater ⭐⭐⭐⭐⭐ Check Price
Hygger 300W Aquarium Heater ⭐⭐⭐ Check Price
SeaELF 300W Aquarium Heater ⭐⭐⭐⭐⭐ Check Price

1. Cobalt Aquatics 300 watt Aquarium Heater (Sleek Design)

Surely, it is one of the best 300watt aquarium heaters made up of resin and thermoplastic material. Thus, this makes its outer body shatter proof and ideal for up to 100 gallons. Moreover, Cobalt Neo-Therm makes sure that you don’t have to worry about the blasting of your aquarium due to excess heat. Therefore, its shatter proof body makes it nearly indestructible.
Cobalt Aquatics 300 watt Aquarium Heater (Sleek Design)

Neo-Therm Slim Body

To begin with, one of the best features of this heater is its thin body which makes it easy to adjust anywhere. Also, it can be fitted in any way inside the aquarium. Similarly, it is designed with the modern techniques for energy efficiency. Also, it comes with a bracket which can be faced either inward or outward of the aquarium.


For the display, the heater has a ‘one-touch’ control system and LED panel. Thus, that allows the display for the current temperature as well as the desired temperature.

Temperature Adjustment

Surely, this 300 Watt heater has many great features. One of them is that, it comes with near accurate temperature control of about ±0.5°F from the actual temperature. 

Automatic Safety Shut-Off

Adding more to it, a special safety feature is the automatic shut-down of the heater. So, once the tank reaches the desired temperature. As a result, its integrated thermal protection helps the glass protect from shattering or over-heating.

  • Shatterproof
  • Easy to read display
  • Smart control
  • Automatic shut-down
  • 3-year warranty
  • Suction cups lasts for month

To conclude, we can say that Cobalt 300 Watt aquarium heater is designed for those who want a heater which is reliable and safe. Lastly, it is nearly invisible in the tank as well as easy to access and control.

2. Ehm  Jager 300 Watt Aquarium Heater (Equal Heat Emission)

This 300 watt aquarium heater is made up of special lab glass which is not only shatter proof but also pollutant free. It does not have any cracks or splits, therefore there is no condensation. Along with this it is chemical resistant.

Ehm  Jager 300 Watt Aquarium Heater (Equal Heat Emission)

Eheim Jager aquarium thermostat heater 300w can be used in both marine water as well as fresh water and is completely submersible. Available in different sizes, it is suggested to place horizontally due to its length. But if kept vertically, the dial comes close to the surface which makes temperature adjustments easy. As well as the package has two suction cups, one long cable and a clamp for safe and easy installation.


The temperature dial has lights which turns on and off indicating whether the heater is working or not.

Temperature Adjustment

It has a TruTemp dial which allows for temperature adjustment with about 0.5°F variation. However, the temperature adjustment needs to be set again after few days. It also has adjustments of a broader range, from 65 to 93 degrees.

Automatic Safety Shut-Off

The best feature of this product is the automatic shut-off mode when the tank has insufficient water. It helps in preventing the heater from running dry.

  • Thermo-safety control
  • Ideal for deep tanks
  • Easy installation
  • Resistant to shock
  • 3-year warranty
  • For tanks that are not deep, placing it horizontally might present a challenge in temperature adjustment.

Best of all, this product is ideal for those with deep tanks for vertical placement as it gives easy access to the temp dial.

3. Uniclife 300 Watt Submersible Aquarium Heater

Equally good performing, this 300watt aquarium heater has no leakage. This feature is due to 2mm thick quartz glass used in sealing it. Similarly, water-tight sealing also prevents it from scalding the marine life inside the tank. Since, the fishes and other animals tend to get too close to the heater as a result it scalds them.

Uniclife 300 Watt Submersible Aquarium Heater

The 300w heater must be inserted completely inside the water. The complete submersion protects the device from burning or shattering the glass. The device can be attached securely to the glass with the help of 3 suction cups.


It has easy to adjust temperature setting, using it through a red knob on the top. Red light switches on while heating and turns off once reached the required temperature. Also, a stick-on thermometer helps in reading the actual temperature of the water when the number turns blue from white

Temperature Adjustment

It adjusts temperature on a wider range from 64°F – 93°F


Automatic-shut off property upon reaching the set temperature.

  • Light on the pocket
  • Easy to handle
  • Automatic shut-off
  • Extra stick-on thermometer
  • Needs to be properly inserted in water otherwise dysfunctions

Uniclife 300 Watt is best for those who are looking for reasonably priced, safe and protected heaters.

4. VIVOSUN 300 Watt Aquarium Heater

Designed with anti-flaming cover with IP68 material prevents scalding. VivoSun 300watt aquarium heater is by far the smartest heater in the market.
VIVOSUN 300 Watt Aquarium Heater

Awarded CE, FCC and ROHS certification and a UL certification for its plug. It can be used in marine and freshwater aquariums.

Setting up too is easy for this heater. This 300watt titanium aquarium heater can be place either vertically or horizontally in up to 50 to 60 gallon aquariums.


The smart LED indicates temp in two colors red and blue. When the digital numbers are red in color they demonstrate the temperature below the desired level while when the number becomes blue it represents the water temperature within the desired range.

Temperature Adjustment

An IC Chip controls the temperature with extreme accuracy with a variation of ±1°F or ±2°F. Also, it has a touch button that allows for external temperature control.


Constructed with material of titanium tube allows it to be explosion proof as well as corrosion proof. It is also built with the protection from over-heating and water shortage.

  • Titanium built
  • Corrosion free and shatter proof
  • Smart temperature display with accuracy
  • Certified by various bodies
  • Replacement after one year is required

Vivosun offers the best and the latest technology under 300 watts aquarium heater category which is easy to use and safest amongst all.

5. MQ Submersible 300 watt Aquarium Heater

MQ 300watt aquarium heater is built with quartz glass to prevent it from shattering as well as covered in a double sealed case and ensures there is zero leakage of electricity.
MQ Submersible 300 watt Aquarium Heater
The heater comes with a long 5.0 ft. cord and is appropriate for 110.120V. Also, it is lightweight and comes with detachable shield and two suction cups.

Temperature Adjustment

With a 2 degree difference the temperature can be set as 68, 71, 75 etc. It has a LCD digital display of temperature.


It comes with an extra thermometer which prevents from overheating or freezing. Also, it is easy to hide in the tank as the body is small and compact.

  • Compact
  • Lightweight
  • Accurate temperature control
  • Detachable shield and 2 suction cups
  • Difficulty in adjusting temperature

This product is good for those who are looking out for a decent, affordable and safe product.

6. Kinbo 300 Watt  Aquarium Heater

In addition to above products, Kinbo has a 300watt aquarium heater with double insulation ABS material. This prevents electricity leakage. Moreover, the quartz glass makes it heat resistant and corrosion free.

Kinbo 300 Watt  Aquarium Heater

It is advisable to use the heater fully submerged and not to be placed in sand or mud. In addition to this, it is also suggested to turn on the heater once completely installed inside the water tank. While changing the place of the tank, turn off the heater first and then wait for 15 minutes.

Temperature Adjustment

The rotating knob on the top of the rod helps in adjusting the desired temperature. Even if there is a cool breeze coming inside the room it will still be able to manage the temperature of the tank.

A wireless diving thermometer allows to read the temperature and remains hidden from the eyes. It is advisable to raise the temperature gradually to avoid explosion due to sudden rise.

  • Easy Control
  • Stable heating
  • All parts must be properly submerged otherwise the rod burns

Over all, it is a reasonable product to buy for those who can take well care of the gadget.

7. Hygger 300W Aquarium Heater

Hygger 300Watt  aquarium heater, which is made with black protective guard is designed and built with premium quality quartz glass. This allows it to be explosion proof as well as corrosion free.

Hygger 300W Aquarium Heater

Most importantly, it has a probing feature which not only tells about the temperature control but also the water level. The device will display mean numbers like E2 and E8. This means that the tank has insufficient water. As a result, it will shut down automatically.

Temperature Adjustment

It has an external built-in IC controller chip for temperature control. A LED digital display shows the current temperature in blue, it changes to red when it starts heating and then turns yellow upon reaching the desired temperature.

Auto shut-off when it over heats and then turns on itself when the temperature drops.

  • LED display
  • Accurate temperature setting
  • Durable quartz tube
  • Loosening of suction pumps

By the end, it is an affordable product with all the latest features.

8. SeaELF 300W Aquarium Heater

Up until now, all the products have shown best of their features. Similar to them is SeaELF, different tone to its name, it has difference in its features as well. This 300 watt aquarium heater is made up of titanium-alloy.

SeaELF 300W Aquarium Heater

It is anti-corrosion and anti-explosion. In addition, it has precise heat reading as well as over-heating censors. It comes with an updated and durable heating wire. Can be used both for salt and fresh water.

Temperature Adjustment

To set the temperature, a button is pressed for 6 seconds to adjust the unit either Celsius or Fahrenheit. Moreover, it is advisable to set the temperature 2 degrees higher than the required temperature. This is because, SeaELF warms up the water 2 degrees less than the set temperature.

Safety Display

Another good feature of this device is that it flashes three numbers E1, E2/E6 and E8. The E1 display is for water shortage or incorrect placement. E2/E6 display means rise in temperature. The user is then supposed to adjust the water level.

The E8 display means the circuit board has broken. Therefore, it is then advisable to contact the company for a new one.

  • Updated and more durable wire
  • Accurate temperature setting
  • Titanium made
  • Tank body made of material other than Plastic or Acrylic should be used

Finally, it is an affordable product with all the latest features.

Buyer’s Guide

Well, we have talked extensively about some of the best 300 watt aquarium  heater products that are available in the market. Now, let’s discuss factors that we must consider before buying an aquarium heater.

Watts Availability

Aquariums come in all sizes and varying water capacities. Therefore, it is very much important to know what your tank size is and how much gallons of water it holds.

This is an important factor to consider while choosing a heater. Because heating products are made for different capacities based on the wattage. So, as a universal rule, 2.5 to 5 watt is required for one gallon of water.

Temperature Adjustment and Readability

So far our review has pointed towards one common thing in all the products. That is every gadget focuses on providing easy, reliable and accurate temperature setting and ease in reading the numbers.

This is an important element, since aquatic lives need appropriate temperature to thrive in. Too low or too high poses threat to their lives

Adjustment of Controls

Like discussed above, adjusting appropriate temperature is very much detrimental to the life of marines. Therefore, all products try their utmost in providing control adjustments to its perfection.


Electronic products pose a threat to life inside and outside beings of the aquarium. Electricity shortage or excess of it is dangerous to both fishes inside and humans outside.

So, another feature to consider is safety from explosion of glass or electricity leakage is another top most element needed to be kept under consideration before making a purchased decision.

The above article has been written in consideration to the best options available to the customers out there. They all have reliability, durability, affordability and above all safety. I wish all the aquatic life lovers the best in making their purchase decision.

May your tiny beings thrive in the warm water and give you continuous peace. Cheers!

Frequently Asked Questions

Q1. How many watts does a heater use per gallon?

As a rule of thumb, for every gallon of water; 2.5-5 watts of heater is used. Therefore, multiply the amount of water with 5 gallons to get approximate wattage.

Q2. Where heater should be placed in aquarium?

The best place is near the source of water supply. This will ensure the water flowing through has the required heated temperature

Q3. Should my aquarium heater be fully submerged?

If the purchased product suggests “Fully Submersible” then it should be done so that way as the element is at the risk of getting dry and might cause an explosion.

Q4. Why do aquarium heaters explode?

Aquarium heaters explode due to pollutants in the water or when the heater is not fully inserted in the water. It can also explode when it is turned on before placing it inside the water.

Q5. Do aquarium heaters stay on all the time?

Generally, yes aquarium heaters remain on 24/7. The thermostat turns off when the water reaches the desired level. This prevents the aquarium from over-heating or explosions

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