After recently installing 2 x Fluval FX6 external filters on a huge 2500 litre cylinder aquarium we are sharing our opinion and thoughts on the FX6 during and after installation

The aquarium: 2500 litres acrylic cylinder aquarium measuring over 4ft on diameter and 5ft in height.

Due to the height of this aquarium we needed an external filter that could cope with a height of 1.5 m to the top of the water to the top of the external filter. After much research the only external filters we could find that would work was indeed the Fluval FX6. This was great news as we have used the Fluval FX5 on many installations and in our opinion for good quality beefy externals that can cope with high waste and through water around, these filters are hard to beat. So it was decided to use the Fluval FX6 x 2.

First impressions of the FX6 did not let us down. The Fluval packaging is excellent, clearly labelled with all the key features such as :-
Self priming with smart pump technology! This smart pump will actually alter the flow rate if needed and upon installation will cut out to evacuate any trapped air, this handy feature also works every 24hrs
New maintenance dial reminders so you can make a note on the filters when you last did a water change or last did a service on the filter
The FX6 seemed to have all the great benefits the FX5 came with such as drainage port at the bottom of the filter,
Self priming plug and start
Aquastop Valves
Multifunctional Rim Connector
ClogProof Strainer
Two MultiDirectional Output Valves

So first impressions where good! Upon unpacking the FX6 we noticed there was not the instructional DVD like there was with the FX5 however it did come with excellent step by step instructions which where very clear. Luckily we didn't need them as setting up was very similar to the Fluval FX5.
It has a nice black sleek design and it truly does look like a very high quality product.
All other connections look the same as the FX5 with very robust quick release connections on the inlet and outlet, both of which with robust taps on, a handy device especially on this installation as our drains will remain flooded so need to be able to shut off the water when needed.
The new maintenance dials are a good idea. They don't count down and bleep or light up or anything to let the user know of when either a water change or service is due on the actual filter so you have to remember to adjust the dial to which month you carried out the task. There is a dial for water changes and one for the filter with a robust click setting so you can point the dial to 1 - 12 months to show what month the task was carried out. We think this would have been better with a month and also date facility so the user can set the actual date not just the month. Some aquariums demand more frequent water changes or filter servicing so a more accurate date setting would have been better. Also a count down dial would have been good such as number of days to the next water change or service on the filter which then maybe lights up or beeps to signal when the countdown timer ends. On the other hand though it is a handy feature.
Flow rates are very similar so everything looks ready to go.

Installation : another great benefit of the Fluval FX6 is they come with Biomax media! Unlike the Fluval FX5! It has circular sponges around the perimeter of the inside of the filter housing from the top to the bottom around 2" thick. Then in the middle there are three huge media baskets. The bottom one with a sponge and room for more media, the central one is packed with biomax and the top basket packed with sponges for the final filtration before returning to the aquarium. We gave the biomax a good rinse inside the Fluval media bags which are also provides making sure no small particles of biomax could not get inside the main filter to cause damage to the impeller. This is something Fluval highlights in their instructions and is very important, any bits of filter media or hard particles can get to the impeller and cause damage so make sure everything is inside the media bags provided. After a quick check over the top of the filter housing is screwed down with the many fastenings provided ensuring a solid tight fit of the lid, under 1.5m of pressure and 2500 litres of water it was reassuring to see how solid the fixings where!
As our drains where externally plumbed to the underside of the aquarium we could not use the provided Fluval hosing as in order to prevent any loops in filter hosing we only needed a small length of pipe from the drain fitting to the FX6, so we opted for the largest Eheim 22mm green hosing which is the perfect fit over the FX6 fittings and also our drain port.
The returns we used the Fluval FX6 hosing. This comes in one continuous length sealed with the connections at both ends, designed to be cut so the sealed ends go on the filter and the other ends pushed into the supplied drain and return fittings also supplied. As these push fitted ends go into the tank you don't need to worry about drips. As we needed extra long hosing to get 1.5 m high we got away with the supplied as we didn't need any drain hosing.

So filters ready, pipes ready, drains and returns ready. Now to fill the 2500 litres which took almost 6hours due to the extremely low water pressure!

After 6 long hours we switched the FX6's on and as our drains where flooded they kicked in straight away! If we didn't have flooded drains and the pipes went up and over the tank then the FX6 are designed to purge themselves but in our case they worked immediately. After a few minutes both filters shut down to evacuate any trapped air. Ok we admit we got caught out and thought there was a problem only to remember this is a feature built into the FX6 so don't worry if this happens. This feature also happens every 24 hrs to evacuate any trapped air!
Then they automatically kicked back in and the first thing that struck us was just how silent they where! We was under the tank working on the lighting units and had our ears very close to the units but had to check they where in fact running as they where just so quiet!!!
As we had a 1.5m head height we was concerned the flow would be dramatically reduced but we shouldn't have worries. We climbed up to test the flow from the twin outlet adjustable flow pipes and they where belting out! A huge turnover of water.

Within a few hours our aquarium was crystal clear! All ready for fish!

Our verdict:

Another excellent filter from Fluval which hasn't let us down. There haven't been that many changes on the Fluval FX6 but when something is so good I think its hard to improve! The maintenance features although a handy feature could have been better but handy all the same! Even at such a high head head height these filters perform with a high flow rate. The filter media capacity is huge and its a truly robust beefy filter designed for big waste, big tanks. If your looking for a quality filter that will run and run without letting you down without too many technical gadgets then this is for you. There is more advanced technology such as Eheim e filters that you can rig up to your PC etc but none are built like the Fluval FX6.

High flow rate
High filter media capacity
Automatic purge feature
Smart pump technology with stop start feature to evacuate trapped air. Also helps keep the running ultra quiet
Very robust and solidly built
Drain port at base of filter handy for water changes
Maintenance reminder dials
Supplied with biomax media

Maintenance reminder dials could be better
No instructional DVD
Not many changes from the FX5 BUT we think its difficult to improve much on an already brilliant filter

Complete Aquatics score : 5 out of 5

Please click on the link below to buy a Fuval FX6 now!