Aquarium Heaters are something I have not had the best luck with over the years. I’ve had them explode in tanks, leak stray voltage in tanks, and get stuck on causing the tank to overheat. I’ll be doing reviews of all the bad ones coming soon (Hydor Theo, Marineland Stealth). So far the only good heater I’ve found is the Eheim Jager, is it a simple looking glass heater.
Eheim Jager Heater
I’ve purchased 3 of the 300 watt Eheim Jager heaters so far and have yet to have an issue. They adjust easily and are calibrated pretty well out of the box. The temperature ring is also adjustable, so you can calibrate it yourself as well. One word of caution – just because your single thermometer does not show what the heater is set at is no reason to panic. I’ve found many Aquarium thermometers to vary, some up to ten degrees. So before you crank the heater up or down, get a temperature gun or other highly accurate method of measuring temperature.
(Click to enlarge) Notice the Hydor Theo 400watt Heater box, it is much shorter. That is because the heater is much shorter. The longer Eheim should dissipate heat more effectively because it has more surface area
The Eheim Jager comes with a pretty nice suction cup mount and a much thicker cord than previous heaters I’ve used. It has a small light which is on when the heater is on, a feature I find useful when using more than one heater in a tank. It helps get them dialed in as close to each other as possible. The adjustment is made via a small knob on the top, very easy.
You can get them in 50 watt, 75 watt, 100 watt, 125 watt, 150 watt, 200 watt, 250 watt and the 300 watt. The 300 watt is the very long, 19″ per Eheim specifications. So make sure you have enough room for it if you need the 300 watt.
Eheim makes some pretty bold claims when it comes to how big of a tank one of their heaters can heat, especially compared to other heater brands. I have not tested the claims because in the instruction manual it states that those claims are only if you’re heating a tank up a small amount. I will add the Eheim Manual specifics later, they may or may not apply to your case. However, if you’re like me and the room your Aquariums reside in gets colder than around 70 degrees, you’re gonna need more wattage than they suggest. For example I have two of the 300 watt heaters in my 150 gallon tank, per Eheim two of them should handle twice that but because the room can dip into the 50’s in the winter I need much more wattage to hold the temperatures steady.
Overall the Eheim Jager seems very well built, holds the temperature well, and the three I purchased are all working well so far. I will update if anything changes in that regard.