Fluval E100 heater review


Gareth Bull has been testing Hagen's Fluval E100 100w aquarium heater.

Fluval have incorporated VueTech, a continuous visual display of water temperature, in their new heater that  comes pre-installed into a square heater guard.  

You may compare this heater to Rena’s SmartHeater but as they are different types a straight comparison may be inadvisable.

The SmartHeater is a composite deemed virtually unbreakable and can be connected in-line with an external filter for better performance. Fluval E-series products are made of more traditional glass.

It’s good…

Included is a bracket that allows you to detach the heater and an adapter enables the heater to be set at a 45° angle. It’s excellent for mounting the heater on side glass and still have access to the visual display — and that’s particularly useful for those with 3D backgrounds.

Setting temperature is simple. Plug in the heater and wait while it self-tests. The heater will then indicate the current level.

Adjust temperature by pushing the lever left or right at the top of the heater.  Each push will adjust by 0.5°C.  The heater is factory set at 25°C/77°F so, depending on current temperature, you may get an alert on the display when first used.

This heater has some non-obvious features, so keep the instruction booklet near.

The heater will visually warn when aquarium water goes above or below the set temperature by 1°C. If water temperature goes off by 3°C the display will also flash.  

The heater will also warn if flow around it is too low but will continue to function when the low flow warning is active.  

I also tested the heater against three separate mainstream glass thermometers. Initially the Fluval consistently showed a reading 1°C below that of the glass ones. However, since the first water change, which meant switching the heater off, it has consistently shown the same temperature as the others.

Fluval Tronic function uses solely electronic components. This means no bi-metal strip to malfunction, which leads to another excellent feature of these heaters — a confidence-boosting five-year guarantee.


There’s little to criticise. The cost may seem prohibitive, but remember that guarantee!

However, there is no visual indication as to when the element is actually heating. Every other heater I ‘ve used has a light that tells you so. Such a visual indicator is technically superfluous with this heater but still something I’d like to see.

The verdict

I would not hesitate to purchase one of these heaters!  

For tanks with external heaters I’ll continue to use Rena’s SmartHeater but, for any tanks where I’d be using an internal filter, I’ll be looking to use a heater from the Fluval E series range.  

The test model has handled being switched off and on regularly every three to four days during water changes and there is a special comfort to be gained in looking at your tank before each bedtime and seeing that all is well with the temperature — thanks to a gentle green light.

There’s also much comfort in using a heater that offers a five-year guarantee if you should ever need to take advantage if it!  

The only reason this product does not get five stars from me is because it does not have an element operative indicator.  

Product: Fluval 'E' Series heater

Price: £35.76

Reviewer: Gareth Bull

Rating: 4/5 


  • Actual temperature display.
  • Warning system with 3 colour display.
  • Versatile bracket.
  • Easy to adjust.


  • Doesn't show when the heating element is on.

This item first appeared in the May 2010 issue of Practical Fishkeeping magazine. It may not be reproduced without written permission.