We will be splitting our review of the Fluval C2 hang-on filter into two articles. In this first article, we will talk about our first impressions, accompanied with a slew of pictures of the C2. In our second article, we will discuss the C2’s operational effectiveness and efficiency.
Our first impressions of the C2 were highly positive. Even before opening the box, we were intrigued about the numerous filtration chambers and excited about how technical the filter was in comparison to the other hang-ons in the market. Needless to say, we are passionate about filtration and the way we gushed over the C2’s box at the store was a little embarrassing.
We got to the office as quickly as we could and eagerly opened up the box like kids on Boxing Day, we were not disappointed. The plastics used for the C2 are very solid, although still not at the same quality as Eheim’s Liberty series. We suspect the reason why the Liberty series has a better build auqlity is because it uses a plastic that is opaque while most other hang-ons, including the C2, uses plastics that are transparent. Although the plastics are a tad lower in quality when compared to the Liberty series, we were easily satisfied with the C2.
The box is well designed, eye catching and full of details. It clearly explains all the filtration chambers, the path of water flow and the provided filter media. With just a quick glance, we knew that the C2 was a serious piece of equipment if all diagrams and claims on the box were accurate. For the first time, a hang-on filter instilled in us a faith that this filter would be on par with the effectiveness of a cannister filter.
The Hagen AquaClear and the Fluval C2 are in many ways similar, and not surprisingly since Hagen is the parent company of Fluval. The effective guidance of water flow through the various filtration media and the control of flow rate are the same in both filters. Also alike are how the filters are packaged and that they come with mechanical, biological and chemical filtration media. The C2 can generally be described as the upgrade of the AquaClear, having better filtration media compartments, better build quality and more up to date technologies.
The C2 boasts a 5 stage filtration process while Hagen’s AquaClear comes has a 3 stage filtration process. Eheim’s Liberty comes stock with a 2 stage and many other hang-ons struggle to effectively implement a proper single stage. Looking at the industry’s track record when it comes to hang-on filters, Fluval’s claim is most impressive.
Taking a closer look at the C2’s 5 stage process reveals that filtration is still carried out by the three main stages of mechanical, biological and chemical, but separated into 5 different sub-stages. Stages 1 and 2 is mechanical, stage 3 is chemical and stages 4 and 5 is biological.
Stage 4 is most interesting. All hang-on filters are constructed in such a way that the front walls of the filter body are lower than the back walls. This is so that as filter media clogs up over time and water inflow is higher than its outflow, excess water will simply wash down the front of the filter and into the aquarium. This design of the deliberate design of the filter body prevents the accidental emptying of the aquarium.
Fluval must be credited here for coming up with an ingenious way to use this flow of water as part of the filtration process. Unlike other filters in which water simply overflow back into the aquarium, the C2 uses this overflow to feed a trickle compartment in which biological media is placed. We were pretty impressed by this innovation.
With the filter body empty of its compartments, one can tell that high quality plastics have been used simply by looking at a picture of it. Instead of the normal transparent body found in almost all hang-ons, Fluval has tastefully used matt plastics for the back of the filter body. There are almost no sharp corners to be found on the body and all corners are stylishly rounded off. Also, Fluval has imprinted its brand name at the back of the filter, all these lend the filter body a touch of class, unknown in the vast majority of hang-ons.
With all the media compartments removed, a plastic plate with holes can be seen. This plate is responsible for the C2’s effective water flow, it blocks water from entering the biological and chemical media prematurely, without first passing through the mechanical media. Most hang-ons do not properly guide the flow of water through the proper sequence of filtration media, thus, filtration effectiveness suffers by a large margin. This guidance is what makes the C2 a proper filter, which cannot be said for other hang-ons without it.
As with all hang-ons, the C2 comes with flow rate control that allows for the strength of water output. Unlike most other hang-ons which depend on a water gate within the inlet pipe, the C2 controls its flow rate by maximizing or reducing the amount of water drawn into the inlet pipe, by its placement over the impeller. The AquaClear uses the same mechanism, but the C2’s feels smoother and better implemented.
The first stage of filtration found in the C2 is the mechanical media stage. The C2 mechanical media was very well thought out, water that flows into the filter is first met by a porous, sponge like material and when it flows through this material, it is then met by a dense foam. The porous sponge filters out the larger solids and particles while allowing the smaller ones to pass, the dense foam then traps these smaller solids and particles and at the same time, polishes the water. A two stage mechanical filtration allows for optimal water flow that last for a longer period of time, as compared to a mechanical filter media which consist of just one type of material.
One major issue in all hang-ons is the way the mechanical filtration media is implemented and this is important as this filtration media is the one the requires the most maintenance. Most hang-ons either do not provide for a effective mechanical media or implement it in such a way that it is troublesome to maintain. Of all our experience with hang-ons, Eheim’s Liberty was the easiest to remove for maintenance but now with the C2, it shares the crown with the Liberty.
With other hang-ons, the need to clean out the mechanical media is judged from the amount of water flow from the filter. A good strong flow will mean that the media is clean, while a slow and sluggish flow will mean that the media is clogged and requires cleaning. In the C2, Fluval removes the need for this observation and adds a visual cue to when your mechanical media requires maintenance. Working on the same fact that a clogged media will decrease water flow, the C2’s visual cue will rise and emerge from the filter body as a slower water flow means an increase of water levels within the filter, resulting in the cue’s rising.
After water flows pass the mechanical media, it then goes into the chemical media if used according to Fluval’s recommendations. However, we will not be using any chemical media as such media will require constant change and is costly over the long run. If a good biological media is used in its place, the filter will have no issues with maintaining an aquarium’s water quality.
All the media compartments in the C2 are top notch in design and in quality. The red basket that was designed to hold the C2’s chemical media was used instead to hold our biological media, Seachem’s Matrix. When we needed to remove the Matrix for cleaning, it was a joy to simply pull it out, no fussing around with nets, or trying to squeeze the netting filled with filter media back into a rigid filter body.
With the mechanical media and the chemical media compartments in place, the trickle biological compartment goes on top of them. This trickle compartment is fed by a sprout from the filter’s inflow pipe as well as any overflows when the mechanical media clogs up.
The top of the trickle biological compartment is covered by a thin mechanical media made out of soft foam. This will prevent solids and particles from falling into the biological media in the compartment and impeding water flow, which is highly vital in the up-keeping of a healthy biological colony.
This mechanical media is placed in a highly accessible location, which is advantageous as it will require the most maintenance as compared to any other filter media in the C2, due to its small size and thin nature. However, clogging of this media will not be much of an issue as the biological media compartment below it is also fed by another source. Such attention to design is a tribute to Fluval.
The trickle biological compartment is too small for our liking as the biological media is the heart of a filter system and space should be prioritised for it. As mentioned earlier, we replaced the ample chemical media basket with our biological media. In this trickle compartment, we placed the same biological media as well.
When looking at the space allocation difference between the chemical media and biological media, it is easy to see that the C2’s main filtration capabilities will largely be chemical. This is not a bad thing as chemical media are far more effective than mechanical or biological media. But as mentioned, the only issue we have with chemical media is its short lifespan, requiring a monthly change to be kept at peak performance. If the C2’s chemical media is constantly renewed, we have no doubts that its filtration capabilities will be better than other hang-ons in the same class.
As with the AquaClear, the C2 comes with a separate box within its packaging that holds its inlet tube, inlet guard, chemical and biological media. It’s nice when such attention is paid into packaging, and reinforce the image of a quality product.
The inlet tube and inlet guard deserves special mention as the plastic used were of an even better quality than the filter body itself. The quality and construction is so good that it surpasses Eheim’s. We were pleased as the inlet tube and guard is a component of a hang-on filter that requires frequent cleaning. Such great quality gives the assurance that this vital part will be long lasting.
Last but not least are the instruction manuals. There were clear and easy to read, with diagrams and information that were designed attractively and easily understood.
All in all, our first impressions of the Fluval C2 are overwhelmingly positive. Look forward to the second part of our review in which we discuss its operational effectiveness.
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