If you have an aquatic pet turtle you’ll need an underwater heater. I have used quite a few, and this is my pick for the best underwater heater for turtles.

These are what I recommend to people who are looking for a good, solid underwater heater for their tank.

Why Your Turtle Needs a Water Heater

Many species of turtle spend the majority of their lives in the water.

Some species, such as sliders and painteds, spend roughly 75% of their lives in the water.

They swim and roam in it, eat in it and even sleep in it.

However, they occasionally need to step out of the water and lay in the sun to bask. This is because:

  •  It dries their shell out to prevent harmful fungi and bacteria from them.
  •  It heats up their bodies again, and is also a preventive measure against bacteria and sickness.
  •  They need the sun’s ultra-violet rays to regulate their metabolism. They also need sunshine for their vision, mood and for healthy breeding.

Basically, turtles bask to heat up and stay in the water to cool down.

However, if the water that they spend the majority of their time in is too hot or too cold, it can have harmful consequences

For instance:

  • Water that is too hot will discourage them from basking, and can lead to too much turtle shell shedding, as well as developing harmful fungi and bacteria.
  • Water that is too cold will discourage them from eating, slow down their metabolism too much and they can easily develop respiratory infections, which are often fatal.

Thus, if you want your pet turtle to remain healthy and vibrant, you will need to make sure the water temperature in your tank or tub is not too hot or not too cold.

For the vast majority of common turtle species, the water temperature should be between 72 and 80 degrees.

The basking area should be at least 10 to 15 degrees hotter than that.

But Turtles in the Wild Don’t Use Them!

Sometimes people will e-mail and ask me why I say that having an underwater heater is necessary. Often times their reasoning is that as turtles are able to survive in cold climates without them, they are therefore unnecessary. Especially since in most cases people keep their turtles indoors.

Here’s the thing.

While it is absolutely true that a lot of turtles are able to live and survive throughout the winter, it’s also true that a lot of them don’t.

Nature is unfortunately very unforgiving, and a lot of turtles, particularly younger juveniles and hatchlings, develop illnesses and infections due to the cold. Others simply freeze to death.

It happens all the time.

The reason I say that underwater heaters are necessary is because it’s a very easy step to take in order to drastically reduce the chances of your turtles developing an illness due to low temperatures. 

Your primary goal as the caretaker of your turtle is to ensure that it is as healthy and vibrant as possible.

Now that you know why a turtle needs a turtle tank heater, let’s move on to the various types of heaters.

Types of Underwater Heaters

There is more than one type of underwater heater for turtles.

That being said, they all generally function in the same way, to heat the water.  There are just some advantages and disadvantages to each.

I’ll briefly describe what each is, as well as some pros and cons to each, moving from the most common underwater heaters to the least.

Submersible Aquarium Heaters

  • Usually rod shaped and placed entirely beneath the water, usually vertically or horizontally
  • Cheap
  • Efficient and can quickly heat water
  • Can be moved to a variety of places inside the tank
  • Usually produces very accurate readings of water temperature
  • Cannot be placed too close to substrate
  • Have to be careful where placed, animals can be burned

Aquarium Substrate Heater

  • Work by placing the heater underneath the gravel, sand or other substrate and heating by coil
  • Better for larger tanks with lots of gravel and plants
  • Maximizes in tank space
  • Very inefficient heating method
  • More expensive

In-Filter Water Heaters

  • The water heater is placed inside the filter (usually canister) and works by heating up the water as its being cleaned and poured back into the tank
  • Maximizes tank space
  • More expensive, and cheap models are usually very poor quality

On top of submersible, substrate and in-filter water heaters there are also hanging and in-line heaters, however typically these are either much, much less common or only for very expensive tanks with plumbing.

Now that you know about the different types of underwater heaters, let’s move on to the best underwater heater for turtles.

What Type of Underwater Heater is Best for Me?

For the vast majority of pet turtle owners out there, a submersible water heater is probably going to be the best choice.

For a few reasons:

  • They are cheap.
  • They are easy to set-up, clean and remove.
  • Their internal thermometer typically renders a very accurate reading.

However, before you go out and just pick any submersible water heater, you will need to figure out one thing.

The wattage.

Here’s an easy way to figure out the highest number of watts your heater is going to need.

Allow for 25 watts for every 10 gallons per 10 degree temperature difference.

If you have a 55 gallon tank:

  • 55 divided by 10 = 5.5
  • 5.5 times 25 = 137.5 watts

Thus, if your room is 62 degrees and you want the water temperature in your 55 gallon tank to be 72 degrees, you will need a water heater that is at least 137.5 watts.

If your room was 52 degrees and you wanted the water temperature in your 55 gallon tank to be 72 degrees, you will need a water heater that is at least 275 watts.

In plain English, just try to remember this when it comes to choosing an underwater heater.

The more watts in the water heater, the better, particularly if you live in colder climates.

The Best Underwater Heater for Turtles

Although there are quite a few underwater heaters out there for turtles, these are the 4 that I have personally used and have experience with.

I would rate them as follows.

Finnex Titanium Hang-on Heater

Out of all the underwater heaters I have used, the Finnex series is my personal favorite. It comes in a ton of sizes, has a large ergonomic outside dial and is high quality.

  • 100 to 500 watts, which means it can easily heat tanks that over 100 gallons
  • Titanium, shatterproof tube to prevent cracking and breaking
  • It is adjustable, from 70 to 92 degrees, in increments of 2 degrees
  • The analog controller sits outside your tank, so you don’t need to stick your hand in the water as with some other underwater heaters for both salt and freshwater. Nice for me because I’m a bit lazy with this!
  • It also has an LED heating indicator to let you know when the device is working and when the correct water temperature has been reached.

Eheim Jager Aquarium Heater

I would have no qualms recommending this EHEIM Jager Aquarium Heater to anyone looking for an inexpensive but reliable heater.

Benefits and advantages:

  • 25 to 300 watts.
  • It can automatically turn off when the water level becomes too low or the device overheats.
  • Has a shock-resistant and shatterproof glass design.
  • Uses an adjustable temperature dial.

Aqueon Pro Heater

The Aqueon Pro Heater is overall good and basically equivalent to the Eheim Jager. I just happen to like the design of the Eheim a little bit better. 🙂

It’s benefits and advantages:

  • 50 to 250 watts.
  • For fresh and saltwater.
  • Is shatterproof.
  • Electronic thermostat.

Tetra HT Submersible Heater

If price is a concern, then I would recommend the Tetra HT Submersible. This is the least expensive of the underwater heaters I have owned in the past. It’s OK, but I would recommend the Finnex or Eheim over this, particularly if you don’t really care to save a few bucks.

It’s benefits and advantages:

  • 50 to 200 watts.
  • Inexpensive.
  • Super easy to install.
  • Indicator light to let you know that the device is on.

Overall, all four of these are fine, depending on the size of your tank and wattage needed.

For larger tanks, the Finnex is awesome but to be perfectly blunt, you don’t need it.  If you just want something that works, the Tetra series are totally fine.

In Summary

  • The use of an underwater heater can drastically reduce the chances of your turtle falling ill when it is cold.
  • Underwater heaters are the easiest method to keep your water temperature within a normal range.
  • In my opinion the best underwater heater for turtles is the Finnex or Eheim Jager heaters.

About the Author

Hi, I'm J and I'm the chelonian-obsessed creator of this website. Feel free to leave a comment below, as unlike a snapping turtle, I promise I won't bite!

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