REVIEW:Fluval FX5 vs Eheim Pro3 compared


MFK Member
Nov 18, 2005


Filters will be compared on
1) Setup and ease of use
2) Flow rate in actual tank situation as % of pump rating
3) Time to convert 40ppm of Ammonia to Nitrate in identical tanks with identical media
4) Actual power costs
5) Cost of running (ie: replacement media costs)
6) Value for money

The review of these two filters is finished thanks to the help of Tony Akasanti from the Singapore University for running many of the tests under lab controller conditions.

Manufactures Specs and Blurbs -


Introduced on Late 2005 the FX5 is Fluval first big cannister filter and contains a number of innovative features
(Specs and product description from the Fluval website)
-50 W
- 3500 L/H (924 U.S. Gal./H)
- Black with orange accents
- 6 foam filter blocks
- For aquariums up to 1500 L (400 U.S. Gal.)
- Additional filter media sold separately
- Height - 17" - 43 cm
- Width - 16" 40.6 cm

The Fluval FX5 is a large capacity, multi-stage external canister filter system. 607 U.S. Gal. (2,300 L)/H, enabling precise management of water conditions for aquariums as large as 400 U.S. Gal. (1,500 L).
A self-priming instant-start system that eliminates the need for manual siphoning.
Unique click-fit AquaStop Valves that regulate water flow, rotate at 55 degree angles and allow for fast set-up and leak-proof maintenance.
A purge valve that allows for partial discharge of debris without needing to move the unit
Multi-directional twin output nozzles to create specific water flows
Fluval FX5 Smart Pump Technology (patent pending) ensures quiet, efficient operation. This self-priming system provides plug-in-and-start convenience.
Lift-out stack of media baskets.



* Dual inlets for perfect water circulation
* New self priming principal
* Maintainence and flow rate indicator
* Large pre-filter - extend servicing cycle
* Adjustabe flow rate
* Castor wheels for easy maintanence
* Ideal for Arowana and big fishes

Technical data 2080
Aq. size up to approx l 1200
Pump output approx I/h 1700
Del.head approx Hmax m 2,6
Power consumption W 30
Heater Power W -
Canister volume l 25
Filter volume approx cm3 12 + 1,5 ( pre-filter)
Dimensions HxWxD mm 567 x 330 x 330

***** NOTE the EHEIM Professional 3 range has been EXPANDED by the new 2076 and 2078 models with electronic pumps putting out 1650 l/ph and 1850 l/ph respectively and featuring electronic self start pumps like the Fluval has ! A 2180 model has also been added with a internal 500w heater !

How we tested:

Neither filter is sold with media included as standard (with the exception of the pads)
In order to make this test fair we used exactly the same high quality media (with the exception of the pads) in both filters. The easiest way to do this (and the way many FX5 owners are going) is to buy the "pack" of media Eheim offer to be sold with the pro 3. This provides exactly the right amount of media for a 2080 filter (and a lot more then enough for a FX5 ..but more on that in a moment) at a substantial discount to buying it separately and can be purchased separately from several retailers. The Eheim media is generally considered the best available and works very well indeed in most brands of filters.
With both Filters filled with media we tested the following.... quoted pump Flow rate vs Actual Flow rate, rated power usage vs actual power usage, noise measured in db at a distance of 1 meter and finally effectiveness of biological and mechanical filtration. We tested the biological filtration by installing the filters on two identical 200cm x60cm x60cm tanks and filled each tank with exactly 700 liters of water. The tanks were both fed a identical dose of pure ammonia @ 4ppm (the correct level for fish less cycling) we then measured the time it took for each filter to have the tank totally free of ammonia and nitrites and producing nitrate at the correct levels. To test mechanical filtration we simply fed the filter intakes submerged tetra bits and then checked the filter baskets to see if any made it through the layers of foam. This method also served to notify if either of the filters had a area of significant bypass for mechanical filtration.
The next part will show the general setup impressions and ease of use comparison.


Setting up eirther one of these is no big deal. We have come a long way from the old Eheim buckets.

The Eheim is unusualy as it has dual imput hoses but this serves well as one can be placed at eirther end of the tank with the spraybar in the middle to improve flow around the tank. The Eheims one piece tap connector is innovative and easy to use if a bit stiff sometimes and it can be difficult to connect the hose to the central connector.The flow rate indicator seems to work well however if you ever left the filter long enough to use use it you shoudl be ashamed of yourself as it takes months and months of heavy use to clog this filter. Another negative with the Eheims set up compared with the Fluval is the seperate baskets they are relitively easy to use but not as easy as the Fluvals one piece set up. The Eheim uses a simple 1 pump priming system that works most of the time with a single pump although we did find ourselves pumping it a few times to get it going now and then and you can actualy see the filter fill up as the cannister body is see through. The filter has wheels so you can remove it for cleaning (beware full of water it weighs a ton) and a tray for placing the pre filter in so you can carry it to a bucket to rinse it out. Its generaly a very easy filter to use in most respects and the fit,finish and fittings scream quality no cheap plastics used and everything is solid. The Eheim is considered the Mercedes Benz of filters and they are built like one ..solid and full of engineering quality that only the Germans seem to be able to do.
The Fluval uses large 25mm hose of a non kink design with seperate taps and this system is possibly the easiest system I've ever seen on a cannister ...just attach the hose in the taps and turn them on and your away it really is that simple. That said for a large filter designed to be used on large tanks the Fluval comes with a bare minimum of hosing just enough to use of a 6x2x2 and your out of luck if you want a bit extra to attach a UV unit or use on a higher then standard tank or cabinet ..come on Fluval ! this amount of hose is absurd ! Another easy to use feature of the FX5 is the central connected media baskets surrounded by the foam (all 25 litres of it !) they hold far less then the Eheim but are so easy to fill and fit back together with the only negetive being that you must remove the whole unti to change the foam on the Fluval where as on the Eheim the foams are changable without removing any baskets. On the upside there is a drain plug (with one of those easy to use click fit taps) on the bottom of the filter so you can drain the water out before moving it which is easier on your back and also offers the ability to use the pump to drain water out of the tank for water changes which is a interesting and innovative feature if you don't need to gravel vac. The Fluval does not have a self priming system per se it must be filled with water manualy before being switched on but there is no sucking on hoses due to its main feature a microprocessor controlled smart pump which when turned on starts the siphon by pumping the water out of the cannister which it seems to do quite well then pausing for 3 mins to allow trapped air to escape.After the priming sequence has finished it restarts itself automaticaly (it can be a long 3 mins waiting for it to restart wondering it its primed itself properly) it also stops itself once per day for 3 mins during normal operation to allow and air that might have been trapped to escape again. Much has been made of this so called "smart pump" and many people have questioned its reliability. We saw no reliability problems with this pump but we cannot say the same of the whole auto prime system. Does this smart pump work? We say "sort of" sometimes it primed itself perfectly but on many occaisions (about 50%) we had to switch it off and start another priming cycle before it was fully primed. The amount of air that stil lescaped after this 2nd priming cycle was substancial enough to say that while certainly a great feature its not foolproof yet.

Both filters are quiet by modern standards but the Fluval is a lot noiser then the Eheim measuring out at 43db @ 1 meter vs the Eheims 19db !
The Fluval is quiet but the Eheim is so quiet you have to check it see if its working !

Filters are used 24/7 365 days of the year so power is important. The Eheim is the clear winner here averaging 27w against the Fluvals 51w so the fluval would cost nearly twice as much a year to run as the Eheim.

Manufactuers rate their filters by the maximum produced by the pump under ideal conditions without media and things like hoses which isn'tvery helpful in the real world. Most cannisters seem to get less then 50% of their rated flow capacity when used in the real world but both these filters did better then that.
The Fluval showed a flowrate of 1991 litres per hour when full of media and connected which is about 57% of its rated pump capacity of 3500 l/ph but the Eheim did even better giving 1207 litres per hour out of its possible 1700 l/ph for a amazing 71% !
This still gives the Fluval a nearly 800 litres per hour flowrate advantage when used in real life situations but filtration is more then flow alone its also about capacity.

Both filters are huge and hold a lot of media however the Fluval contains 25 litres of foam media around the sides of the baskets and only will hold about 6 litres of bio and mech media in its baskets while the Eheim holds a full 12 litres of bio and mech media and only has about 2 litres of foam.

Will the bigger flow rate of the Fluval make up for its lack of media ?


Mechanical filtration
We wanted to test the ability of these filters to remove particals from the water so we emptied a big container of tetrabits near the intakes. The Filters both did a great job catching most of the gunk in their pads but if I had to give to one of them I'd give it to the Fluval that 25 litres of foam really can catch some gunk!

Biological Filtration
The most important function of a filter is its biological filtration capacity and here is the best test for these filters. The clear winner here was the Eheim taking only 11 days to cycle the 700 litres of water from 4ppm of ammonia to Nitrate only vs the FX5's 13 days. It just shows that that extra 6 litres of bio media in the Eheim more then makes up for the 800 litres per hour flow advantage the Fluval has. a 2 day difference is quite significant and its more then we expected.

CONCLUSION A matter of price
While the Eheim is the clear winner in the performance stakes the decision is not clear cut. The Eheim is the better biological performer and has a better % flowrate when full. Its a lot quieter and holds a lot more media and uses less power then the Fluval. So its a no brainer to the Eheim on most areas right? Well no ... The Fluval still does a excellent job its a bit easier to set up and it does a slightly better job at mechanical filtration and and here is the big kicker .... IT IS ABOUT HALF THE PRICE OF THE EHEIM So while the Eheim is clearly the better filter here I cannot honestly say its twice as good as the Fluval... issues of reliability and longevity not withstanding. If moneys not a issue its got to be the Eheim but the Fluval is a very good filter and its attractive price is going to win it a lot of fans. As for me personally I like the Eheim better but I also have a few FX5's for tanks where I can't justify the cost.
The only real winner here is us ...we have 2 great filters to choose from that both do a great job.


Jack Dempsey
MFK Member
Jan 9, 2006
new jersey
great review MFK thanks you:thumbsup: :thumbsup:


Feeder Fish
MFK Member
Apr 26, 2007
where my cichla are

thanks so much for posting this comparison, it's a BIG help, not only to me but probably for many MFKers.


Feeder Fish
MFK Member
Apr 26, 2007
Very well thaught out comparison and very close results concidering the differance in price.
379.00 + 107.00 for the media pack for the Eheim pro3

199.00 + 45.00 for media FX5


Feeder Fish
MFK Member
Mar 29, 2007
S.E. Michigan
Excellent review, thanks for posting it. I guess if you want quiet (living room, bedroom) the Eheim may make the most sense, but if sound isn't as important then the price of the FX5 is a big plus.