Fluval FX4 High Performance Aquarium Filter, Canister Filter for Aquariums up to 250 Gal.

Absolutely! Hands down the best canister filter out there. If you don't have one and you're waiting, stop, go get it now, you won't regret it. There is no noise. It's easy to install. The flow rate is superb. Water clarity is spectacular. You couldn't ask for anything better. Go get you one! What are you waiting for?

The Fluval FX line of filters is a real work horse which rarely goes wrong if you do the upkeep on it. I use one on the tank I have my turtle in, and it keeps the water crystal clear, even though the old boy digs a lot an tries everything he can to cloud up the water. If I take it off line for cleaning (which is a breeze) or maintenance, it will get the water clear again within an hour if the turtle has been very active while it was off, and much sooner if he wasn't moving around too much. He's a very active turtle, and a very messy eater, but he's neither active enough nor messy enough to overwhelm the FX-6. I also use an FX-6 on my hillstream tank which requires a lot of flow. It pushes the water through at a very good clip so that the stream has a pretty good current for my hillstream loaches and for my rainbow shiners to run in when they're getting ready to spawn. I have the FX-4 on a 20 gallon tank which is probably just a bit overpopulated, But again, it is a good enough filter that it keeps the water quite clean. With surface skimmers on my tanks, even the water's surface is clear. To clean the filter media, all you need to do is lift the media baskets out, the use the filter's bucket to clean the sponges and reusable media, replace the media which has broken down too much to be reused, or which uses chemical treating, then either empty the old water out and replace it with fresh clean, or keep the old water if it's not too bad (it is almost always too bad). The reason you clean the media in the water the filter bucket has in it is so that you don't loose any of the beneficial bacteria which is growing in it. The FX series of filters have variable flow valves, which is a nice feature, though many filters have that. If you close the valves before opening the lid of the filter, you don't have to worry about draining the hoses, and they will be good to go when you turn the filter back on and open the valves. No priming needed. Everything in this filter is easily repairable if something goes wrong. If something happens which wears out the impeller, it's very easy to take the old impeller out, and drop a new one in. It's also easy to replace all the O-rings when they get old and start to loose their ability to seal the unit. If you're unlucky, you might need to do that once a year, but it's more likely that you'll just need put new lubricant on them. I am mechanically challenged, so if I find it easy to take care of, I'm sure just about anyone will be able to do it. I have had problems with several of the other big brands of filter makers, but I have never had a Fluval FX series filter go south on me. I recommend them to anyone who wants to keep their fish's environment clean and healthy. If I ever start another tank, I'll definitely be buying another Fluval FX.

Ive been running the Fluval for about 3 months now, and I am absolutely OBSESSED with its quality. I have a 75 gallon tank with a turtle and pleco (both produce A LOT of waste). Previously I was a die hard Penn Plax Cascade fan for the last 5 years, but my last two had motor failures and they changed their warranty terms finally, so I decided to switch it up. Long ago I wanted a Fluval, but but the price was steep so I settled for less and let me just say it’s the best investment you can make. It’s quiet (don’t know why other reviews say it’s not unless they are keeping their water levels really low), my tank remains crystal clear with my normal monthly maintenance routine, and it is easy to clean and change out my media. The fasteners are really not that complicated and don’t take that long to unlock like other reviews say. The canister itself is designed so that it is air tight and I’ve had no signs of leaking. The outtake is made so you have two options to direct the flow of your water which is helpful if you have a basking platform above half of your tank. Highly recommend.

I have two turtles and their tank was always so dirty! I have gone through 6 HOB filters and two aesthetic turtle filters (ones that look like rocks) and every filter I tried needed to be fully taken apart and deep cleaned every few weeks! Nothing could keep my tank clean until I got this filter! I waited a few months to write this review just to make sure it held up and it is still absolutely amazing! I was nervous because I have never had a canister filter before and I didn’t know how to use it but it’s actually incredibly easy. It’s effective, super quiet, and total game changer for my turtles! Now I’m thinking of switching all of my tanks to this filter! It saves me so much time and it saves money because I don’t need to constantly buy replacements for the HOB filters anymore!

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.

*UPDATE* Instead of giving advice or suggestions, Fluval customer service decided to blame me and my light sources aka natural light. I told them multiple times that my turtle tank isn't near natural light and that I never had a problem with other filters with heated lamps. I even cleaned out the filter and the tank AGAIN without light and still algae. It also GOT GREENER!!! My poor turtle is stuck in a smaller tank till I can purchase a new filter or until I can figure out the problem myself. Then the customer service rep flat out told me their filters aren't meant for turtles 😐. I have had this filter for a little over a month now (close to two) and I am extremely disappointed! This filter has not cleaned a thing! Then the water started to become super green! I cleaned out the filter as well as the media and noticed algae all in the filter. I added new media hoping to clean the water a bit better AND YET algae is still growing. So (as shown in the second picture) and completely cleaned the tank and emptied out all the gravel. I completely cleaned out the water and added fresh water the old fashion way and still GREEN WATER! This filter has caused me nothing but trouble and my poor turtle has to stay in a small tank (because I couldn't afford a bigger one for him to temporarily stay in) until I figure this out. And no, algae removers/reducers aren't helping! A $300+ canister filter and it has not cleaned crap!

I have had other Fluval pumps, the build quality of the FX series is significantly better. The self prime function is fantastic and worth the money just for it. No more pumping to get the pump to flow.

I have a painted turtle who makes a giant mess of her aquarium over time. I am lazy and want to clean the tank as infrequently as possible, so I get large canister filters like this one that I can leave for a month or more before needing to clean it. My previous filter was a Fluval and lasted quite a while, so I decided to stick with that brand. This unit is quite an upgrade over my last Fluval which was a "lower tier" unit. So far I have been mostly happy with the unit overall. It is quiet and has really good throughput. The reason I didn't give it 5 stars, though, is because just like every other brand out there there is just so much breakable plastic and less than beefy construction, considering the price. Honestly, from my research, I don't think there is a canister filter out there that I would rate a 5 star. For the high price, the connections seem cheap, the hoses seem REALLY cheap, there are just so many ways that a filter like this could be better. Oh well, I won't complain TOO hard since it is doing a good job of filtering. One thing that did happen to me, though, is that the filter starting filling with air to the point it was blowing bubbles pretty much all of the time. The problem was that the joint where the flexible hose connected to the rigid tube of the input side was above water so air was getting in. I reconfigured things so that the hose / rigid pipe joint was under water and haven't had an air issue since. This should NOT be necessary, of course. If everything wasn't cheap friction-fit plastic but rather had substantial connections with hose clamps or some other method of connection, it wouldn't matter if your seams were above water. One last positive I will say is that the multi-directional return head is nice to keep the water well stirred up in the tank and avoid "dead zones" where crud can accumulate - they got that right.