Eheim Jager Heater: Everything You Need To Know

The Eheim Jager Heater is renowned as the best available aquarium heater available for your pet aquarium from fish to axolotls to turtles!

The main reasons are its performance and durability.

There’s a lot more to the Eheim Jager heater than performance and durability so let’s dive in and learn everything there is to know about this wonderful aquarium heater so you won’t hesitate to get it over the others…

What Sets The Eheim Jager Aquarium Heater Apart?

aquarium heaters

Shatterproof/Heat Resistant Glass

The Eheim Jager Heater is made from laboratory-grade glass that was thoroughly tested in scientific labs by true scientists.

If you research online, you will find horror stories about aquariums and heaters cracking. You don’t have to worry about this with the Eheim Jager heater.

The glass is also pure, which means it is free of pollutants and resistant to biological and chemical substances.

The Eheim Jager glass also has a large heating surface to allow for even heat distribution. The glass also can handle a wide variety of heat temperatures, which helps keep it from cracking and prolongs the life of the heater.

The Tru Temp Dial

The specially designed dial precisely adjust the temperature with a range of 18° to 34° C (65° to 93° F).

With other heaters, the temperature may not be as precise as it should be, but with the Eheim Jager heater, the temperature accuracy is within +/- 0.5° C. That is less than a degree!

The Thermo Safety Control

This is a special feature that automatically shuts the heater off if it leaves the water or if the water leaves it.

So, if you are doing a water change and the water level falls below the edge of the heater, the heater automatically shuts off so you don’t have to worry about readjusting it.

If you end up with a dud of a tank, your tank could crack and lose all of its water while you are gone or sleeping. It sucks when this happens, but at least with the Eheim Jager heater, your heater will shut off and not burn itself out.

The On and Off Indication Light

This is simply a light that lets you know if your heater is working, so you don’t have to stick your hands in the water to feel the heater or feel the water to see if it is warm.

Suction Cups and Mounting Bracket

Very easy to put attach the bracket to the heater, place the suction cups on the bracket and then attach the heater to the side of your tank.

Extra Long Power Cord

This might not seem like a big deal, but since the heater is fully submersible the cord will have to run up and out of the tank before running to the nearest electrical outlet. Also, you will need to do a drip loop before plugging it in.

Pro Tip: A drip loop is simply making sure the electrical cord runs along the floor or touches the floor. This is in case something goes wrong with the aquarium-like glass cracking and water leaking out. With a drip loop, the water will run along the cord to the floor and not into the electrical outlet, which we all know is not good.


Your water temp is very important. If the temperature drops or rises too much while you are gone, your fish could become ill or even die.

The Eheim Jager heater already has a great reputation that has stood the test of time, so you can save yourself a headache by purchasing the Eheim.

All you have to do is type ‘aquarium heater’ into amazon and then sort the results by average customer rating. The Eheim Jager heater has the highest number of reviews by far in the top results which is great when it comes to the overall average.


Jager heaters surprisingly have very competitive prices despite their performance and reputation.

Checkout Eheim Jager Heaters Online

Caution! Make Sure Your Jager Heater Is Properly Placed In Your Aquarium and Calibrated!

How to Setup and Calibrate Your Eheim Jager Aquarium Heater

Your Jager heater will come with easy-to-follow instructions but otherwise here it is.

  • Remove the contents from the box.
  • Attach the suction cups to the bracket.
  • Attach the bracket to the heater.
  • Turn the blue dial till the desired temperature lines up with the red arrow.
  • Place the heater in the aquarium vertically(if possible, an angle if necessary to be fully submerged) by pushing the suction cups against the glass. It is best to place it close to the outflow of water from your pump or filter, so the water is heated as it comes out.
  • Plug your heater in with a drip loop as discussed above, making sure the power cord goes down and touches the floor before it goes back up to the power outlet. (this ensures any water that leaks down the cord goes to the floor and not the electrical outlet.

Make sure you have a reputable glass or digital thermometer to read the water’s temp to install in your aquarium with the heater.

How Do You Calibrate a Jager Heater?

  • After you have your Jager heater and thermometer up and running, the temperature you set the heater to should be the same as the thermometer. (this is why it is important to buy quality equipment)
  • If the temperatures don’t match all you have to do is move the red pointer on top of your Jager heater to what the temperature is actually reading on the thermometer.
  • Jager heaters are usually set at the right temperature right out of the box but sometimes you do have to calibrate it.
  • If possible, it is best to calibrate your heater in a separate tank or even in a 5-gallon bucket in case the temperature is too far off. This is mainly if you are not at home during the calibration.
  • If you are home, you should be able to monitor the water temperature. The problem is, if the temp gets too high or low, your fish could become ill or even die.

Notes, if you do this in a 5-gallon bucket, it is faster, just make sure you use a bucket that has never been used for anything but your aquarium and make sure you rinse it out with straight water. Never use soap or chemicals.

Other Frequently Asked Questions About Your Eheim Jager Aquarium Heater

Can Eheim Heaters Be Fully Submerged?

There is a line on the Jager heater that indicates where the water level needs to be. However, you can fully submerge your Eheim heater. The line just means the water level needs to at least be at or above this line since Jager heaters are designed to be fully submerged.

How Do I Know if my Eheim Heater is Working?

There is an indicator light that comes on when your Jager heater is plugged in and working. You will also be able to tell it is working if the aquarium thermometer is reading the desired temp that you have your heater set at.

Can Eheim Jager Heater Be Mounted Horizontally?

The Jager heater is fully submersible, so it can be mounted at an angle or horizontally. The instructions actually recommend mounting it horizontally.

Where are Eheim Heaters Made?


What Size Heater Do I Need for my Fish Tank?

The general consensus is ‘5 watts per gallon of water’, but it never hurts to go up one more size. This is for tanks 55 gallons or less. Once you get above 55 gallons, it is recommended to go 3 watts per gallon. If your aquarium is somewhere that gets cold, it is recommended to use two aquarium heaters, spaced apart in the tank, so you don’t end up with any cold spots in your tank.

Ss an Aquarium Heater Necessary

It is usually best to use an aquarium heater to be on the safe side, especially if you live somewhere cold or if you have a tropical fish. An aquarium heater keeps the aquarium water in the proper range of temperatures that fish species are used to in their wild habitats.

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