Fluval Heaters Review 2019: Are These Worth it?

at 12:46 pm

Fluval M Series premium heaters are quality manufactured in Europe using superior components and construction.

The Fluval M Series Submersible Heater is safe for fresh and saltwater aquariums. Submersible to water line on heater.

European-made aquarium heater boasts quality performance

Shock-resistant glass heater mirrors aquarium surroundings

Maintain proper water temperature AND aquarium aesthetics

Fluval M Heater Review

Finding a good heater is becoming more and more difficult these days and having historically had such good luck with Fluval Tronic Heaters, I decided to try Fluval’s latest heater, the Fluval M.

It was a mistake.

Ignore the “Reflective Technology” marketing hype. It’s a bad simulation of a mirror. It does not hide in the background at all. But that is not the real problem. My heater only lasted about 3 months in 55 gallon tank containing nothing but a Pleco. It will still heat the water, but cracks are clearly visible in the glass, so it has been removed and trashed. A closer inspection identified water has indeed made it into the heater. A disaster waiting to happen.

Might work great in a tank containing small fish (like guppies and tetras) but this heater cannot be recommended in anything containing fish of anything approaching substantial size. The heater certainly should not be considered for an Oscar Tank (or any large cichlid). You’ll also need to apply caution when performing maintenance or cleaning. A decent accidental bump of the heater against the glass may cause breakage.

ModelLengthMax. Aquarium SizeMax. Depth
50W11"15 gallons8"
100W11"30 gallons8"
150W13"45 gallons10"
200W13"65 gallons10"
300W15"80 gallons12"


  • Steady Temperature: While it lasted, it maintained a very steady temp.
  • Appearance: Disregarding the marketing hype, the heater is a sleek looking heater and the blue light (means on) indicator is cool (in the true sense of the word).
  • Easy to Adjust: The temperature knob is very easy to move in small increments, which allows for smooth adjustments of the temperature


  • The darn thing has cracks in it after 3 months of use, from nothing more than a Pleco.

Fluval E Heater Review

Finding a good heater is becoming more and more difficult these days. Due to the habit of Marineland Stealths exploding and their subsequent recall I needed new heaters for my Oscar Tank. Being an Oscar tank, use of the Eheim Jager heaters was not an option as they are a glass heater (and, for some reason, Heater Guards are not available). While there are various titanium heaters on the market, research identifies few of them get decent reviews and those that do are generally very expensive. This left me with two basic options, a Fluval E or a Rena Smartheater (note: this was written before the Aqueon Pro was released, it is a very viable option for an Oscar tank). Having had such historical good luck with the Fluval Tronic Heaters (albeit not so good luck with the Fluval M), I decided to go ahead and try the Fluval E.


  • Mounting Bracket: The heater easily clips on or off of the slim line mounting bracket or can be vertically adjusted for precise placement.
  • Precise Temperature Setting: With the easy to use adjustment lever, the temperature can be precisely set in 0.5° increments.
  • integrated heater guard offers advanced protection for fish and invertebrates
ModelLengthMax. Aquarium Size
50W10"up to 15 gallons
100W11-3/4"up to 30 gallons
200W13-3/4"up to 65 gallons
300W13-3/4"up to 100 gallons

I made a good choice. I am happy.

Don’t let the “high technology” marketing scare you away. The technology is used to make things simple, not complicated. I’ve never owned a heater that was easier to “set” a desired temp. The LCD display makes it very simple to identify the current temp and the fact that the display changes colors makes it very simple to determine temperature safety at a glance (Red = Too Hot, Green = Just Right, Blue – Too Cool).

I’ve been using this heater for several years and have not experienced any issues. Many of the design concepts associated with the Fluval Tronics were transferred over to the Fluval E and I’ve had a Fluval Tronic in use for almost 20 years. If the Fluval E is anywhere near as reliable, it’s worth every penny.

As for comparison to an Eheim Jager? The quality of glass used in the Eheim is obviously much higher. The Fluval E glass quality would be closer to a Fluval M. However, the Fluval E does come packed inside a very sturdy heater guard and has stood up well to my Oscar’s attempts to rearrange the tank.

The Fluval E is an excellent choice for an Oscar Tank.


  • Steady Temperature: Heater maintains a very steady temp. I have only a single 300 watt Fluval E running on a 120 gallon tank and am having no problems maintaining a steady 80 degree temp.
  • Ease of Use: I’ve never had a heater that was easier to set and monitor. To adjust the temp, simply move a level at the top of the heater left or right (to adjust up or down) and the LCD display will identify your selected temperature.
  • LCD Display: Easy to read display serves multiple functions. Not only does it eliminate the need for a secondary thermometer (which are another hazard in an Oscar Tank) it also allows you to notice, at a glance, temperature safety via color changes in the display.
  • Heater Guard: Any heater placed into an Oscar tank must be indestructible (or close to it). This is either accomplished via the heater being constructed of non-breakable material or via protection of the glass components by a sturdy guard. The Fluval E glass components are well packaged inside a sturdy heater guard.


  • Cost: Heater cost more than standard heaters but is lower in cost than quality Titanium Heaters.
  • Unplug During Water Changes: This should be done for any heater, even ones identified as “self shutoff”. However, I would consider it an absolute requirement for a Fluval E Series Heater.

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