Review: Eheim Jäger Thermostat Heater




Review Eheim Jäger thermostat heater

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I bought the Eheim Jäger thermostat heater from a Dutch online store for the betta tank a while ago and wasn’t really sure what to expect. On one hand, I loved my Eheim canister filter. On the other, I was given an Eheim heater by a friend before, which turned out to be broken even though it was quite new. But since everyone is always very enthousiastic about Eheim products, I decided to take the gamble! After all, the 75W version (for aquariums up to 26 gallons/100 L) was $24, which is quite reasonable.

The heater looks good. They’re almost always a bit obnoxious, but at least it’s not bright blue like my Superfish heater. The cord is long enough, it has the handy lamp to show whether it’s on or not and it has a run dry protection, which prevents cracked glass and dangerous situations if you accidentally forget to turn it off when doing a water change. The heater also allows recalibration if necessary. So far so good!


I ran the heater in the 16 gal/60 L betta tank for a few weeks and everything seemed fine until I noticed that it did not heat the aquarium evenly. This was probably due to the fact that there is not much water circulation in a betta aquarium due to betta’s dislike of strong water flow – putting the heater in a horizontal position instead of vertically fixed this probem. Something to keep in mind, but luckily it’s easy to fix. The heater is fully submersible so the horizontal position has not caused any problems.

The heater keeps the water temperature at a very consistent 80.6 °F/27 °C, which is great! I sleep with my window open even when temperatures get very low, but the heater handles the temperature fluctuations in my room just fine. It’s currently only set to 73.4 °F/23 °C, but the difference in temperature can be explained by the fact that the lamp gets very hot. Recalibrating should fix this, but it’s not actually necessary since the tank is at a safe temperature.

All in all, this heater works very well. It’s reliable and the temperature has been consistent for a few months now, which is great. The run dry protection has saved me some trouble multiple times and the heater is easy to hide with a few plants. I’d probably buy it again if another heater broke.

So is this the heater for you?

Yes, if you’re forgetful like me and need a heater with run dry protection, and if you’re looking for a very accurate heater that allows very small temperature changes and recalibration if necessary.
No, if you keep puffers of other scaleless fish. This heater does not come with a heater guard – scaleless fish can get seriously hurt if they touch a heater, so you may want to go for something safer to be sure.

The Eheim Jäger thermostatic heater is available in 9 sizes for up to 265 gal/1000 L. You can buy it on Amazon!

Eheim AEH3617090 200-watt Jager Heater for Aquarium, 16-Inch
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Hope you guys enjoyed the review. I’ll hopefully be reviewing more products soon. Happy fishkeeping! 

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2 thoughts on “Review: Eheim Jäger Thermostat Heater”

  1. Hi Mari,
    I have four moss balls (Marimo) which I keep in glass bowls for decorative purposes.
    I recently purchased a 5-gallon tank & filter system for my betta.
    Is it safe to put my moss balls in the tank with the betta, or will he tend to nibble on them?

    • Hi Cindy,
      Bettas are carnivores, so he won’t be interested in the moss balls at all. The only point there might be is that the temperature bettas prefer is a bit high for marimos, but I’ve been keeping a marimo in my betta tank for months and it seems to be doing fine. I’d say go for it!


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