Fluval FX6 High Performance Aquarium Filter, Canister Filter for Aquariums up to 400 Gal.

One awesome filter! Quiet and clean! Highly recommended. I run on my freshwater 75gallon tank and works great!

I have always been a hang on the back filter guy. After getting a new 60 gallon tank, I decided to make the switch. This filter has been nothing short of amazing. It was so easy to set up and worked perfect right out of the box. The cleaning process has also been super easy. It also has the ability to change the filtration that you need at any time. Overall an amazing filter that I will continue to use.

I have kept fish for about 50 years. I have experimented with many aspects of the hobby, studied everything, and done trail and error. Now I just run one 150 gallon tank, but at times have had many. I also have out door ponds.What I know is that most crap you read from so called experts on the web are "crap". After 50 years the basics are the same. The equipment has improved.Most people have no clue as to what a filter can do or should do. Go to my forum at yardcraphome dot com and open the critters section.I hooked this fx4 in today. I have been running the older fx5 (new model is fx6) for years and consider it a good buy. The fx5 had some challenges as to leaks and easy to break clamps, but suspect/hope they improved with the fx6/fx4 update. The fx5 is very good, best filter I have owned.Flow rate is important, but also is volume. These fx6/fx4 are huge.If you just want flow, buy a circulation pump. What you want is the water to pass over lots of helpful things before returning to the tank.I use multiple filters for different things as that helps as to maintenance. . One (fx5) is mainly for biological which is by far the most important. Due to the great 900 gal output, have it hooked to a a Tetra Pond bio filter that they claim handles 4000gal (doubt that). That reduces flow rate, but the combination is over kill for biological in my tank. The two together are like a large, but closed sump filter which can hold lots of bio material.The now dead Fluval 300 (or something?) was for chemical and needed replacement. I looked at filters to replace it and almost went with the new Ehiem 600 (great filters), but in the end got the small brother of the large Fluval that is still working great after years. I decided on the fx4 as opposed to the fx6 due to the fact the volume was enough when just for chemical, and I don't want my tank to become a rushing river. One thing with these is adjusting flow rate is very easy so maybe should have gone with the fx6.I hooked it up today and the only problem was a leak at the input connection. I wrapped some Teflon tape and easy fix. I filled it with Chemi-pure (because I have used it for decades) and and Purigen (which is just an excellent product). The flow rate is not that much more and my fish friends are large fish.I don't think flow reduction will be needed.My opinion is that for many, the fx4/fx6 is a best buy.The down side is they are large. Large is also the good part, but maintenance must be done from time to time so keep that in mind. These are heavy. I have a small room with a sink where filters live and tubes pass through the wall, so easy for me.My 3rd filter is the Fluval G6 which is a joke. This would be good for a nerd type with a small tank with low fish levels. I only keep it hooked in for the mechanical cartridge (no where near as good as the older Magnums, but very easy to service). Mechanical filtration occurs with all filters and while nice, should not be the focus of your filter choices.

I bought an FX5 in 2011. Seven years later it is still running like brand-new.I bought an FX6 in 2013. Five years later . . . .like brand new.I've been keeping fish for more than 25 years. During that time I've used many different types of canister and HOB filters. My main recollection with previous canisters was the rage and frustration of priming them, fitting finicky rubber gaskets, dozens of fussy parts. . . After those experiences, the FX5/6 were such a joy. They're simple to assemble, and they prime immediately.Nothing is perfect, so here are pros and cons to help the prospective buyer:PROS:1. Huge capacity. Imagine a 4-gallon bucket filled with media, with a powerful motor in the lid.2. Moves a lot of water, and keeps the tank sparkling.3. Starts instantly and runs like a dream.4. Reliable - I've been running an FX5 continuously for 7 years; and an FX6 for 5 years. I've never once had any repair issues or problems of any kind. The only maintenance I do is clean or change the media as needed.CONS (and these would probably be better described as "things to consider before getting one").1. Powerful enough to suck up fish. In my 120g, I previously had jewel cichlids. They spawned, and whenever I would clean the filter I would find babies inside. Again, this is not a defect, this is just a cautionary note to be smarter than I was about where you use the filter. I currently have guppies in the 120g. They have hundreds of babies. Again, on any given day I'll find a dozen babies in the filter. (FWIW, you can adjust the flow, although I'd suggest that if you need reduced throughput, you might just get a smaller and cheaper filter).2. It's heavy and awkward. Hey, it's a 4-gallon-ish bucket filled with water and filter media. It's heavy. As another reviewer noted, I have to heave it out of the cabinet and haul it outside to maintain it.3. You may need to tinker with the selection and placement of filter media. A Google search will yield multiple hits from people who have suggestions and opinions on the topic. I may still be doing it wrong. From bottom to top I have a water polishing pad, two foam pads, and ceramic tubes. For some reason, the polishing pad gets saturated first, and ends up being the reason for reduced flow, while the others are only somewhat dirty. My tank is moderately planted, and I can go through perhaps 4-5 weeks between filter cleanings/media changes.4. You'll want a towel when disconnecting the filter from the hoses for cleaning. I have not found a way to keep about half a cup of water from escaping whenever I disconnect.5. It may take some elbow crease to depress the "buttons" (wrong term) to release the hose from the filter body. You have to depress them and lift the hose off, and sometimes it requires some effort.6. Expensive. It just is. That's a lot of money to drop on a filter. But I think it's well spent. I imagine you're paying for a powerful and well-built motor. No other piece of aquarium equipment (excluding the tank, of course) has lasted me 7 years - let alone in like-new condition. I feel that I easily have another 7-plus years out of it.Bottom line? I see no need to look for alternative filters for large tanks. I just bought a 300g aquarium, and when it arrives I will be furnishing it with another FX5 or FX6.

When I tell you that this product is worth every penny it costs, please believe me. We have only owned this for a couple of days, however, the difference between the filters we previously purchased (and we have had at least three of the standard ones) and this product is night and day. This is so whisper quiet, it makes me wonder if it is actually on! And it makes the tank water very clear. Definitely worth the money!