9.9.2011

I've used many power filters and canister filters in the past and was really looking forward to adding the Fluval C2 to my small 10.5 gallon heavily planted aquarium. I've tried many AC (AquaClear) power filters in the past and they were my go-to, but after discovering Fluval had their own offering I had to try it.Since my tank is heavily planted, I did not use the carbon filter. Why? Because plants need carbon dioxide. With that said, if you don't use the carbon filter you basically have one step before you're ready to put it on your tank. Just rinse the whole thing and put the biological things into its basket. It's really a piece of cake.I added one extra step a few days after installing it and that was since I wasn't using the carbon filter I decide to open that bag up, dump the black stuff in the trash, heavily rinse it, and then put in my own biological substrates into it. I used my Eheim substrate and plopped it into the bag and voila, even more biological filtration!Pros of the Fluval C2:1. Awesome design with the water trickle and the whole removable cartridges for quick cleaning. The telescope design for the intake is really neat and something I've never seen before. This way you can get the exact height you want. The plastic parts of the filter also seem durable and strong unlike others I've tried.2. Very flexible. As I mentioned, there's a whole extra compartment (if you're using the carbon filter which I recommend against... sure it makes things pretty but I recommend growing plants in your tank because they add a whole new element and are great for the fish and water quality) and you can add in your own substrate into that area. You can even opt to use your own substrate in the little biological basket instead of the ones they give you. If you want, you can use your own sponges and stuff for the mechanical filtration but I think the one they give will last a long time if you just rinse it. I also use a pre-filter (Fluval's own pre-filter sponge they sell for their Edge lineup) because I have Red Crystal shrimp and I don't want any babies to get sucked into the filter. The pre-filter I recommend because it'll prevent the gross things to go in the filter, but will also be trapped to the side of the pre-filter (giving fish and shrimp something to nibble at).3. The water flow is very good and you can control it. I am using the C2 on a small 10.5 gallon tank filled with glowlight tetras and red crystal shrimps and I like to put the water flow to max during the day, then move it over to lowest when their lights go off. The extra flow I noticed make the fish more active (possibly more oxygen going through their gills?)Cons of the Fluval C2 (the one caveat; read this if you get a noisy one!)1. When I first got the filter I was pissed because it was indeed noisy. You could hear the movements of the spinning motor and I thought this thing was a piece of garbage. After 2 days of running it and listening to it (I keep my tank on my desk at my work so I sit next to it) I figured it would never be quieter and did some research online. Turns out this has happened to others. The solution? Lube up the motor parts! How? I used regular Vaseline (bought the travel size at my grocery store). Unplug and take apart the filter at a sink and have a bucket/large-cup handy. When you separate the motor from the rest of the filter you can remove the metal spinning thing. I went ahead and put a thin layer of Vaseline on the surface of that, but it was probably not necessary. The main culprit you want to lube up is the thin metal needle it attaches to. You could use a Q-Tip or thinly rolled up paper towel to get Vaseline around it. I also put Vaseline at the hole of the larger metal thing (the one you took off) and so when it was inserted into the needle the extra Vaseline would go over the needle. From there you could try out the filter at your sink (this is where you can put the intake into the large cup or bucket) and see if it's quieter. If it's still noisy, try again and maybe use more Vaseline. You can of course use better lubrication for water/aquariums but I read Vaseline is safe to use.After doing this the Fluval C2 was really quiet and perfect! Hopefully you won't have to do the above fix, but given the pros of the filter I wouldn't let that you sway from owning this gem. It's a quick fix and afterwards you have a great silent filter!

17.5.2018

Great filter, but not perfect!Mine arrived with several cosmetic scratched on the outside of the filter. It looks like some dust from the bio media in the box got loose in the box and scratched it up. I would suggest to Fluval to better package their contents as well as maybe rethink using a clear plastic as the HOB housing.The matte parts of the housing looks much better, in my opinion, and was not as susceptible to scratching like the clear portions (actually, no scratches at all on the matte surface). Since the filter hides behind the tank, I'm not going to be splitting hairs over it, just a little disappointed since you expect something brand new and sealed will look as such.While it can be pretty quiet,it's not as quiet as my Fluval U3 underwater filter. But it's filtration capability and capacity is superior. It did take a few weeks for it to quiet down, it was very noisy in the beginning. I even applied some vaseline to the shaft. So patience is needed for it to quiet down.Sometimes when unplugging it and plugging it back in after doing scheduled maintenance, it can be a little noisy. This usually quiets down. The other times the noise sounds like a buzzing or rattling. Power cycling the filter a few times seems to resolve this (must be the impellar and shaft being slightly out of center), my smaller HOB filter used to do the same thing (might be a HOB thing). The lid can buzz from time to time if not secured properly, I've got a small decoration that sits on top to prevent it from buzzing.Filtration capability, filtration capacity, flow rate, and custom filtration options are all top notch. The basket used to hold carbon can be used for many other filtration options. Once my inital carbon filter that came with the filter became depleted, I swapped it out and put some extra bio media (Seachem Matrix) as well as a Purigen bag in there. In a squeeze, I was also able to add a small filter floss bag of carbon too, but that was pushing it. If I had one negative regarding its filtration, I would say that the bio screen above the bio media clogs up a lot quicker than I would expect it to. Mine I feel like I am cleaning out more than once a week since it gets to a point where more water wants to flow over it instead of through it, causing water to run off over the edge the bio media compartment. while it is easy to clean and rinse, it leaves me a bit concerned about keeping it in place when away for an extended weekend or vacation. I'm wondering if cutting out a foam filter would do just as good and be less likely to clog.Maintenance on the filter is very easy, even easier than the Fluval U3. I grab one of my small 1 gallon quarantine tanks to put the filter contents in. I will then either fill than with some tank water and clean each component or I will rinse them in the 5 gallon bucket I do my water with. Put everything back together and turn the filter back on. Maybe 5 minutes of work.It would be nice if the extension tube that comes with the filter was a little bit longer or at least pack in a short extension add-on without having to buy one separately. In my tank, which is around 18.5"-19" tall, the stock extension tube fully extended stops about 3"-3.5" above my substrate. It would be nice if I could get it closer to about 2" from my substrate.

6.3.2011

I purchased the Fluval C4 about 3 months ago. Thus far it has kept my water absolutely crystal clear.Overall: I'm very impressed and very pleased with this HOB filter. I'd recommend it to anyone looking for a nice all-in-one filter with easy maintenance.Here's a list of some nice features:-Better use of the space available in the filter box compared to other HOBs - Many other HOBs have dead space where there isn't any type of filtration happening. This filter has been effectively designed to allow maximum filtration in the space provided.-Very nice all-in-one filter - Mechanical, chemical, and biological filtration all efficiently incorporated into the filter box.

12.11.2016

The C4 Power Filter is a very nice filter, but has one major flaw (IMHO), First the Flaw or Concern. This filter is not self priming, meaning that you have to pour water into the motor area of the filter to get it going properly, you only have to do this once and the filter will hold its prime and your filter is working...BUT, if the power goes out the filter will kick back on when the power comes back on but because it requires you to pour water into the motor area the pump will not pump water, it will run and make lots of noise but the water will not be flowing. That is the first issue, but only the beginning, the third stage of the great filter holds some x shaped stone media that beneficial bacteria will grow on and you will never have to change this media,

23.11.2012

For reasons I don't understand, hang-off-the-back (HOB) filters seem very unpopular in the UK. I like them and this one in particular because1. I don't like having an internal filter taking up lots of space and looking ugly2. Removing the sponge for rinsing is so much easier than with an internal filter (and button pops up to tell you when to do it)3. It's a fraction of the price of an external filter and there's less risk of flooding your floor4. No objective measure of this, but with its big sponge, trickle-down biological compartment and third compartment for extra sponge/biomedia (officially for carbon but few seem to think it worth spending money on), it seems to offer really good filtration compared with more internals5.

20.3.2011

I've tried many different filter types in conjunction with small (10-20 gal) aquariums over many years and until recently had narrowed my choices down to either the Aqua Clear or the Penguin Bio-Wheel. The Aqua Clear filtered water through media, but never really trapped much debris. While the Bio-Wheel did both, filtered and trapped, it was noisy and the replacement media used a lot of plastic and they were relatively expensive.I recently decided to try the Fluval C2, made by Hagens, who also makes the AC. In fact, when unpacking the C2, I first thought it was the AC in different packaging, as the form factor is similar and it has a familiar look to it. But look and feel is where the similarities end.

9.8.2012

Second purchase review* from 9/27/2012Great filter although the C3 I just received had a crack almost the entire length of the return spout. Will epoxy into place although it works fine the way it is for now. Read below for review on original C4 purchase.The Good - I love the adjustable flow rate. Turn it low for feeding and high for the rest of the day. The 5 stages of filtration are also great. You can clean any one of the 5 stages without much hassle. There is even a peg that pops up to let you know to clean or replace the poly foam pad when its full of debris. It has a large chamber which you aren't required to use a unique bag type for your filter media in which I've purchased a nylon bag from a local store for about a dollar and fill it with my own mix of carbon and zeolite.

9.1.2012

While trying to decide between a canister and a HOB filter for my new 55 gallon I stumbled on this new Fluval filter. I read all the reviews available, which aren't many, and decided to give it a try. I got the C4. When I received it I was very impressed with how easily it goes together. This will be an absolute snap to clean and maintain. I absolutely love how it forces the water through certain paths to make sure that it flows through the media, not just around it.I've been using it for a few days now and it is by far the most quiet filter I've ever owned. I've always used the bio-wheel filters before and had always considered them the only choice.

2.3.2015

The Fluval C series sets the standard for HOB filters. It is built solidly, permits simple adjustment of water flow, provides excellent mechanical filtration, contains a wet-dry section for biological filtration, and has plenty of room for chemical filtration. I use Purigen by Seachem, which does a terrific job of keeping my tank sparkling clear. It is very quiet. In fact, I need to look at it to make certain that it is running. If you keep your water level high enough you won't even hear the water as it re-enters the tank. The mechanical filter is a two sided pad. The pad sits at the back of the filter, and is easily removable. One side catches coarse materials, and the other is finer for the much smaller particles.

14.5.2012

I purchased the C2 a few months ago and it's been running on my dwarf puffer tank with no issues. In fact, this filter runs very efficiently in keeping the water clear and the parameters within good levels. Since Hagen makes both the AquaClear and the Fluval C-Series of filters, you can expect 'quality' from this HOB filter. I have the AC 20 running on my other tank which I love too. However, this C2 filter seems to be an updated and more refined version of the AC filters. I like how the C2 has a telescoping intake tube. I also like how the compartments are all modular in that it gives you some flexibility to customize what media, sponges, and other filter additives you choose to run in it.

23.5.2013

I think this is the first item I've ever actually returned to amazon.Bought this for a small tank with goldfish and it actually worked really well at producing clean water. Had it installed for hours and the water was crystal clear. Unfortunately the noise was intermittently loud and when we took the motor off the filter to investigate the next day, the housing for the motor was chewed up (impeller contacting the housing?).Contacted customer service for help, given a case number and told to wait up to 3 business days for a response. No response, so back it goes. Going to order another one to see if it is just the one we received - since we liked how it worked so well.

23.8.2017

I have alternated between canister filters and over the tank filters for many years. I transitioned back to this filter because I trust the Fluval brand, and because filter media is more readily accessible than for my canister filter which is Sun brand from China, and whose media I can only find online. I also disliked the "gunk" that accumulated in the extension hoses from the filter to the intake and output tubes on my canister filter. This small filter has an amazing output, almost a little too much for my 50 gallon tank as I have to unplug it to prevent fish food from sinking immediately, but I also wanted powerful filtration for my acrylic tank.

4.5.2014

This filter started working quietly for just a couple of hours in my 10g gold fish tank. Noticeably, the water quality now is way better and clearer as compared to the water earlier. I took a peek on how it works before writing this and it started to suck up some debris that my Ferplast Blucompact Internal Filter and Resun HOB Filter (combined) cant take in. Though, it is still early to give my full comments, i know for sure that this will do its job. Assembly was a breeze and was very easy to prime.I was surprised too about the rattling noise being commented on this, i just encountered it during the priming stage. I found out that the intake tube wasn't perfectly intact/

14.9.2019

I really have to start this review by saying that this filter has serious packaging issues. I had my first one returned because it seemed like I have got a refurbished one since it had so many scratches on the body and a grain-ish/sand-ish material all over the filter. It comes out that the filter media isn't properly sealed and it will scatter around grains that will have your filter all scratched out of the box. That's the one and only reason why I'm taking away the 5 stars for this filter.But moving on to the filter itself, I have no complaints. I have read complaints about the noise, but it's really pretty quiet. Of course, it will make noise, and especially if the water level is below the water exit,

14.6.2014

Filter was as expected. Space design for fitting on back of the tank could be improved, as the plastic frame did not allow the filter to sit all the way down on the side of the tank. Sat about 1/2 inch higher. This did not seem impact the over all performance, but did make the water flow louder as it was falling back into the tank from a higher distance.Also, the shipping could be improved. We ordered 1, it came damaged. The motor connection was broken. Ordered replacement, it was fine. We decided we wanted 2 filters for our 75 gallon tank with about 35 tropical fish, ordered another it came damaged. Ordered a replacement & the motor was LOUD. The fan wheel was tilted inside the fan housing and clicked as it ran.

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