Best Aquarium Heater for 20 Gallon Tanks

Aquatic heaters are an essential piece of equipment for any fish tank, but choosing the right one can be a challenge. In this article, we will introduce some of the best aquatic heaters for 20 gallon tanks and explain why they are worth considering.  First and foremost, it is important to choose a heater that is properly sized for your tank. In general, you will want a heater that can provide around 2.5 to 3 watts of heat per gallon of water in your tank. This means that for a 20-gallon tank, you will want a heater with a wattage of around 50 to 100 watts.

But just grabbing any 20-gallon aquarium heater might not work depending on your circumstances.  While many aquarium heaters offer similar features, there are specifics that should be considered before purchase.  A heater is essential for your fish’s health and happiness and a good one will make them feel comfortable and calm. Many fish rely on the temperature of the water to keep them warm because they may not produce body heat themselves. 

There are both internal and external heaters.  Obviously, the external heaters sit on the outside of the tank and are generally more powerful than the internal ones.  The internal ones are usually in-pump heaters that sit on top of the gravel.  Whichever one you decide on, be sure to do a fair amount of research on each product.  Read reviews online and check out social media groups related to aquarium hobbyists as they are a great resource for knowledge about products and what works for people getting into the practice.  Aquarium heaters are just one piece of the massively detailed puzzle that needs to work well with the other parts to ensure that your tank is a success.

best aquarium heater for 20 gallon tank

Best Aquarium Heater for 20 Gallon Tanks

There are many different choices for 20-gallon aquarium heaters, so we have compiled a review list of some of the top options for aquarium heaters for 20 gallon tanks.  Each one has its own specifics, but are highly rated as some of the best aquarium heaters.

Fluval Aquarium Heater E200

View Item on Amazon

The Fluval Aquarium Heater E200 is a reliable and effective option for keeping your fish tank at the proper temperature. The 20-gallon aquarium heater has a durable and sturdy design, with a high-quality heating element that provides keeps your tank water at the desired temperature. The included temperature controller allows you to easily set and maintain the ideal temperature for your tank, and the clear display makes it easy to monitor the current temperature.

One of the standout features of this particular heater is its safety features. The heater is equipped with a built-in thermal shutdown feature that automatically turns off the heater if the aquarium water temperature gets too high. This helps prevent overheating and potential damage to your fish and tank.  Another advantage of this heater is its energy efficiency. The heater is designed to use minimal energy, which can help save on your electricity bills. It’s also easy to install and use, with clear instructions and a user-friendly design.  Overall, the Fluval Aquarium Heater E200 is a good aquarium heater for anyone looking to keep their fish tank at the right temperature. Its safety features, energy efficiency, and ease of use make it a reliable and convenient choice.


  • Energy efficient
  • Trusted brand
  • Easy to use


  • A bit expensive

Hygger Aquarium Heater

View Item on Amazon

Another one of the best heaters on the market is the Hygger Aquarium Heater.  This is a powerful 200-watt submersible aquarium heater that is made with premium quartz.  It is resistant to explosions and any corrosive elements, which keeps your fish safe from any scalding action.  You can set the temperature of your tank water without having to put your hands inside the water.  The Hygger Aquarium Heater keeps the water at an ideal temperature and comes with an easy to read blue LED digital display.  While this brand comes in a variety of sizes, the 200 watt is ideal for any 20-gallon aquarium heater.  For a quality fish tank heater, check out this brand to keep your water temperature at the right setting for your aquatic friends.


  • Comes in variety of sizes
  • Good price
  • Good customer service


  • Not as long lasting as other 20 gallon aquatic heaters

Eheim Jager Aquarium Heater

View Item on Amazon

The Eheim Jager Aquarium Heater is a highly regarded product among aquarium enthusiasts. Its advanced technology and sleek design make it a top choice for maintaining a consistent and healthy water temperature for fish and plants. The heater is easy to install and comes with clear instructions for use. The digital display allows for precise temperature control, and the heater itself is built to last, with a durable construction and shatter-proof glass. This brand comes in a large variety of size options and is perfect for any 20-gallon aquarium heater and is set a very reasonable price.  Aquatic creatures are sure to appreciate the stable water temperature provided by the Eheim Jager Aquarium Heater, which can help them to thrive and live longer, healthier lives. Overall, the Eheim Jager Aquarium Heater is a reliable and efficient option for maintaining the ideal water temperature in any aquarium setup.


  • Small in size
  • Reasonably priced
  • Wide variety of wattages


  • Bad customer service reported

Marineland Aquarium Heater

View Item on Amazon

The Marineland Aquarium Heater is a fantastic 100-watt heater that comes with an adjustable temperature dial that is easy to use.  It also has a mounting bracket that fits snug along your 20-gallon aquarium tank.  With its sleek design, this aquarium heater has a thermal switch which automatically turns off if the aquarium water exceeds the desired right temperature.  One of the standout features of the Marineland aquarium heater is its ability to maintain a consistent water temperature. This is essential for the health and well-being of fish and plants, as fluctuating temperatures can lead to stress and illness.  Another key component of this 20-gallon aquarium heater is that it is energy efficient, which extremely important to people who want to reduce their electric bills and carbon footprints.  If you are looking for a quality aquarium heater, then check out the Marineland Aquarium Heater.


  • Auto turns off if exceeding temperature
  • Affordable
  • Energy efficient


  • Quality issues

Top Fin Aquarium Heater

Top Fin Aquarium Heater provides an automatic shut-off feature and accurate temperature control to make sure that your aquarium water does not cook your fish.  This automatic shut-off function is an important safety feature that keeps your fish from becoming fried fish.  The quartz glass tube that the heater is made of holds strong and is shatter resistant.  This is a quality fish tank heater that is completely submersible, but does not change the water level.  While this 20-gallon aquarium heater is a smaller heater, it delivers a powerful control over your water temperature.  The Top Fin Aquarium Heater is only available at PetSmart and is set a reasonable price.  It is perfect for smaller tanks and provides good control for your aquarium.


  • Auto shut off feature
  • Reasonable price
  • Double-layer design


  • Quality issues

Aqueon Adjustable Pro Aquarium Heater

View Item on Amazon

The Aqueon Submersible Pro Aquarium Heater is a reliable and efficient option for maintaining the ideal water temperature in any aquarium setup.  With an easy to install feature, this 20-gallon aquarium heater makes the perfect choice because of its clear digital display that allows for specific temperature control.  This gives you precise control over the warm aquarium water.  Plus, this aquarium heater is nearly indestructible and is a fully submersible.  The Aqueon Adjustable Pro Aquarium Heater has a LED indicator light, which tells you when it is actively heating the water. 

Aqueon Submersible Aquarium Heater

View Item on Amazon

The Aqueon Submersible Aquarium Heater is another powerful submersible heater.  This is one of those small aquarium heaters that work best with tanks that are under 75 gallons.  However, if you are looking for a 20-gallon aquarium heater then you would only need the 50-watt option.  It has suction cups for easy installation and has an auto shut-down feature if the water becomes too warm for any tropical fish.  This brand of aquarium heaters works with both freshwater and saltwater to provide precision warmth for your fish and plants.  It also comes with an LED display that lets you know that the water is being heated.  The Aqueon Submersible Aquarium Heater is a quality heater that gives a great value for its cost, seeing as it is very reasonably priced and stays fairly accurate to the desired temperature.  This is one of the best heaters because of its near indestructible design, which can be positioned in your tank vertically or horizontally.  Check out this handy aquarium heater for your tank.


  • Good value for money
  • Auto shut-off feature
  • Easy installation


  • Suction cups weak

Best Budget Aquarium Heater for 20 Gallon Tank

Getting into aquarium building can be quite expensive, especially considering all of the different parts required to make it successful and clean.  If you are looking for a budget aquarium heater that does the job while keeping a very low price, then check out the Hitop 50-watt adjustable aquarium heater.  It is a submersible glass water heater that is perfect for a 20-gallon tank.  This particular brand is considerably lower in price than any of the other 20-gallon aquarium heaters and comes highly rated.  The Hitop 50-watt aquarium heater has a long service life and keeps the temperature quite accurate over time.  This is one of the best budget aquarium heaters for any 20-gallon tank. 

Heater Size for a 20 Gallon Tank

When you are dealing with a 20-gallon tank, then you need to have a 20-gallon aquarium heater.  It is quite common for many people to think that they can purchase a bigger aquarium heater for their tank only to find out that the heater is ONLY meant for larger tanks.  This can cause considerable damage not only to smaller tanks, but it will likely kill all of your living creatures inside the tank.  This is why planning your tank’s contents is paramount to successfully having a tank that works for your aquatic friends. 

Therefore, for a 20-gallon tank, the heating element should only be between 50-watt heater should be plenty of heat for your aquarium water.  Since the size of the tank is so important when considering the wattage, you will not need much when getting a 20-gallon aquarium heater.  Anything less than that will not properly provide enough warmth for your aquatic creatures and plants to survive.  Anything higher than that will certainly kill your fish, especially if they need lower temperatures to survive.  You could use a 100-watt heater for a 20-gallon tank, but there are more possibilities of issues coming up in the tank.  Make sure that when you are buying your 20-gallon aquarium heater, you are checking the specifics of the product so that it aligns with not only the size of your tank, but also provides the correct temperature for your plants and aquatic creatures inside. 

Remember that the aquarium heater is very important if you are looking to provide the best quality of your fish’s lives.  Additionally, each fish has its own set of preferences for aquarium water.  Tropical fish, for example, enjoy water that is around 74 degrees Fahrenheit.  Luckily, most aquarium fish operate in a temperature range somewhere between 73 to 82 degrees. 

How long does it take to heat up a 20-gallon tank?

Keep in mind that heaters are going to take some time to get the temperature of the water to the desired degree.  The average gas tank water heater will take about thirty to forty minutes to heat up the entire 20-gallon tank of water once its positioned and turned on.  For most electric heaters, it can take about twice as long for the water to get to the desired degree, so you will need to wait between an hour and an hour and twenty minutes.  Gas tank heaters generally have a stronger heating element and can warm the water fairly quickly.  Regardless of which type you use, make sure to always keep a close eye on the water’s temperature, especially after you put living creatures inside. The temperature will at some point reach the temperature you want, but it will then be your job to make sure it stays that way. Since you are dealing with such a small-sized tank, the 20-gallon aquarium heater should be able to warm your water fairly quickly. 

Where to place aquarium heater in a 20-gallon tank?

When considering where to place the 20-gallon aquarium heater, it will ride completely on which type of heater you get.  Is it external or internal?  Does it have a clip or does it use suction cups?  Is it fully submersible?  All of these are important questions when considering the position of the heater.  As mentioned before, most in-tank aquarium heaters will sit towards the bottom of the tank by the gravel and heat the water up from there.  The best location for placing the external and submersible heaters are anywhere near the maximum amount of water flow.  Usually, the area around the outlet of the filter or in the stream of a powerhead will have the strongest water flow.  Putting the heaters close by to this water flow will better allow the heated water to disperse throughout the tank.  In the case of a 20-gallon tank, one aquarium heater should be enough to maintain control over all of the aquarium’s temperature. 

What type of aquarium heater are available for 20 gallon tanks?

Throughout this article, you may have noticed references to all types of different aquarium heaters for 20-gallon tanks.  Just in case you are not familiar with the differences between these types, here is a list of the available types of aquarium heaters.

Submersible heaters

As the name suggests, the submersible heaters can be completely submerged under the water without any issues.  They usually come in long, slender tubes that can stick to the side of your aquarium via suction cups, hooks, or a few clips.  This type of heater is one of the more effective types of heaters because of its ability to just sit in the water and do its job.  It can sit either vertically or horizontally, although most displays on the heaters are horizontal, so that might be the most convenient.  That way, you will be able to see the temperature more easily.  Since heat rises, it is recommended to place the heater near the bottom of the tank to strengthen the heat distribution. 

Immersible heaters

Another type of aquarium heater are immersible heaters, which are only partially able to be under water.  There are parts of the mechanism that need to stay dry.  They are generally made of glass tubes with a heating coil on the inside of it.  More people have seemed to choose the submersible heaters because of their ability to be completely underwater, which makes immersible heaters slightly out of date.  But they do work just as well to keep your water warm.  They also come with the same features as a submersible heater like indicator lights, cut-off switches, and markers to show correct levels of water.  Both of are easy to install and work very well once in place. 

In-line heaters

In-line heaters are the type that operates outside of the aquarium, much like a filter.  One of the biggest advantages to using this method is that it more evenly distributes the heat throughout the water because it is not inside the aquarium where there might be some hot or cold spots.  This is a great option if you have a larger aquarium to deal with, so it really wouldn’t make for a very good 20-gallon aquarium heater.  In-line heaters also need to be aligned with the filter and be strong enough to warm the entire aquarium.  They are easy to install and keep your fish healthy and happy. 

In-Sump heaters

An in-sump heater is a completely different tank, vessel, or container that sits outside of the aquarium, where water flow through a network which heats up the water.  Sumps can be single chamber containers or have multiple chambers that each have a specific purpose of heating and filtration.  The advantage of in-sump heaters is that they hide a lot of equipment that normally go in the tank, like filters and heaters.  They also add a lot more water volume which helps keep the parameters more stable.  While this is an incredibly efficient method of heating your water, it is more likely that you would use the 20-gallon tank as the sump itself.  This is another method that would work best with tanks over 50-gallons. 

Titanium aquarium heaters

The advantage that titanium heaters have is that the heat usually dissipates more rapidly than a sump or any other enclosed space.  They can be placed directly inside the aquarium and are very durable and hard to break.  The heating element inside these types of heaters is also quite efficient and warming up the water.  Furthermore, they are incredibly accurate in getting the precise temperature you desire because of the sensor built inside the heater.  However, once again, titanium heaters are used for very large aquariums, but they do not make such a good choice for 20-gallon tanks. 

Substrate heaters

Substrate heaters are typically used as an add-on to other heaters and act more as a support for those primary heaters.  These types of aquarium heaters come in the form of cables that connect to the bottom base of the aquarium.  The best part about of these heaters is that they promote gentle water movement and encourage root growth in any plants that you have.  Nowadays, substrate heaters are not as common and they can cost a fair amount as well.  However, there are many other advantages to having one in your tank, most especially the concealment of the actual heater itself.

Leave a Comment

Your email address will not be published. Required fields are marked *