Eheim Jager Aquarium Thermostat Heater 300w Reviewed

It can be hard to find a good heater for your aquirium. I have just finished reviewing the Eheim Jager Aquarium Thermostat Heater 300w.  But did it live up to expectation ?

Eheim Jager Aquarium Thermostat Heater 300w

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Eheim Jager Aquarium Thermostat Heater 300w Specifications

The Eheim Jager heater has the following specifications

  • Fully submersible
  • Thermo safey control protects against running dry
    Will automatically turn off when water level dips too low
  • TruTemp dial recalibrates the heater for precise temperature regulation
  • Made of shock resistant and shatter proof glass for fresh or marine water
  • On/Off indicator light for at-a-glance monitoring

The Eheim Jager heater comes in many different sizes. Using the table below you will be able to work out what size heater you will need for your tank.

Tank Size Heater Power Heater Size
7-16 gallons 50 watt 9″
16-26 gallons 75 watt 10.2″
26-40 gallons 100 watt 12.2″
40-53 gallons 125 watt 12.2″
53-79 gallons 150 watt 13.4″
79-106 gallons 200 watt 15.7″
106-159 gallons 250 watt 17.3″
159-264 gallons 300 watt 19.6″

Eheim Jager Heater Setup

I will now take you through the setup of the heater.

Whats In The Box?

When you receive the heater the following items should be inside.

  • 1 x Eheim Jager Heater with 190 cm power cord
  • 2 x Suction Cups
  • 1 x Mounting Bracket
  • 1 x Instructions
  • 1 x White Plastic Ring

Eheim Jager Heater 300 Setup

Make sure to read the instructions before setting up the heater with your tank.  The white plastic ring can be thrown away, it was only used to keep the heater safe during shipping.

My first impressions of the Eheim Jager Aquarium Thermostat Heater 300w was wow this looks like a well built heater that will last. I was surprised how robust the glass feels, it is advertised as being shatter proof which I now believe.

Heater Setup

First thing we need to do is set the temperature we want the heater to run at.

How do I set the temperature on my eheim Jager heater? You can set the temperature to between 18° to 34° C (65° to 93° F) by twisting the red dial on to the temperature you wish to use, as shown below.

As far as I know 65° to 93° F is the largest temperature range you can get for an aquarium heater.

Next connect the two sucker cups to the mounting bracket as shown below.

Eheim Jager Heater Sucker Cups

Now connect the mounting bracket to the heater and click in to place as shown below.

mounting bracket heater

Heater Placement

You can now place the heater in to your tank

How to place eheim Jager heater in my tank? simply place the two sucker cups on the glass on the inside of your tank. .  Be aware that the power cable is quite thick and might be an inconvenience for your placement of the heater.

It is recommended to place the heater at the opposite end of the tank to the pump.  This way it should heat up your tank quicker.  Once the heater is in place connect the power cable to the mains.

Heater Placement

Expect the heater to heat the water very quickly.

I am not to sure what to make of the thick cable? I guess it makes the heater extra safe, but is it needed? I have never known an aquarium heater to have an issue because of the cable.

Monitoring The Temperature

Now we have the heater in place it is a good idea to monitor the temperature of the water.  If the pump was to stop working there are no obvious signs it is not working and your fish will suffer as a result.

I highly recommend you purchase an aquarium thermometer to monitor the water temperature. I use the Capetsma Aquarium Thermometer (Shown Below) which I love because it has a built in alarm that you can set if the water temperature goes below or above what you set.

Capetsma Aquarium Thermometer

In my tests I used the capetsma aquarium thermometer and a Fluval Celcius Digital Aquarium Thermometer to monitor the water temperature and I found that the Eheim Jager Aquarium Thermostat Heater 300w was very accurate at warming the tank to the selected temperature.

I found that the temperature was out by about 1°F which I believe it very acceptable.

Overall Thoughts

I think that this is one of the best glass aquarium heaters on the market today.  Especially considering how much it costs.  This is a well made affordable heater that I highly recommend.

  • Feels well built / high quality
  • Very good price
  • Heater will shut off when removed from the water
  • Very accurate
  • Designed for use in both freshwater and saltwater
  • Highly rated on amazon
  • Power cable a bit bulky










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