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

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 purchased this for a 20 gallon tank to help with cloudy water from algae as my little Aqueon filter couldn't hack it. I took it out of the box and whoa, it's a beast! I thought maybe it was going to be too much filter for the tank, I was wrong, it's a great size. The canister itself goes together very nicely and both inlet and return connectors are clearly marked and very strong. The hoses are beefy and very stiff, which is the only troubling issue that I'm dealing with. The very simple and small instruction pamphlet suggests to soak the hoses in warm water to make them more pliable. I did this, it worked ok, until the hoses got back to RT. The tube sizes are quite large and the tank lid does not sit flush. I belive I will change to a tank mounted light rather than a top. I've found the intake tube to be very long and is sitting at the bottom of the tank, I'm not really a fan of that, but so far it seems alright. Priming... well, the priming pump on the canister is smooth and has decent suction unless there is a lot of air in the canister, and this made priming the tubes quite frustrating. I'm not an expert, fairly new at keeping fish, and I've always used a hang on the side filter, so this was a new method of filtration. It took me about 15-20 minutes to get the tubes properly primed and full, how I did it still not sure, but when it happened, outflow was nice and steady. The instructions did not have any suggestions or methods to make it easier, and as a new user of a canister filter, I would have liked to have had that. I'll have to make some adjustments with the tubes but that's a minor inconvenience. This filter is definitely worth the money, you shouldn't be disappointed.

OK, SO! A few things that I hope will help you out as much as they helped me! 1. Get some silicone grease and grease up the big o-ring that comes in the lid and the 4 o-rings that are on the input and output tubes, on the top of the lid. Only takes like a pea-sized bit for the small ones all together, and probably a couple pea-sized bits for the big one, depending on how dried out it is. There's one on part of the motor, but they DO grease that one up already. There's also apparently maybe some inside the intake and outake mechanisms, and the drainage one, but I couldn't figure out how to get to those. Anyway, this'll make those o-ring gaskets last way longer. 2. The output should be longer than the input, but both should not have slack. This is because mumble mumble something something physics. I don't know. Somebody said it makes a difference, so I did that. 3. The intake is VERY LONG and you can make it LONGER but not SHORTER. This is a big problem if you are using the filter in, say, a 75 gallon with sand substrate. That intake will touch your substrate and also will suck up your sand. In fact, if you have sand in any tank you are using this with, you want to put a sponge over the intake at the least... I used a hacksaw to shorten that intake tube, then connected it to an eheim pre-filter. Unfortunately, the pre-filter is charcoal grey and stands out like a sore thumb. Fortunately, it'll help immensely with avoiding getting sand in your cannister, both by not being way down on your substrate, and by having some sponges to help avoid sand and large things getting sucked in in the first place. 4. Really, REALLY make sure that those intake and outtake connectors are CLICKED into place, all the way down, or you will have a flood. 5. Really, REALLY make sure you put water in the cannister before plugging it in. I somehow almost missed this step while I was geeking out with the filter media. 6. Don't overfill those baskets or they could break. 7. Expect construction to take a long time, and be fiddly. 8. Make sure there isn't a bunch of slack in your hoses. They shouldn't go down and then up... only up! Anyway, I just set the thing up. Being careful, doing some extra steps, and struggling with getting it all put together correctly took hours, but it seems to be running great now! I'll come back if it suddenly fails for no reason, haha. It's so big, for my 75 gal it almost counts as a sump, I swear! It looks like a shop vac. For this price, they should have given more options for the intake. A shorter sponged pre-filter or something. In black. That'd be nice.

I've been keeping tropical fish for over 50 years, and I know quality when I see it. In point of fact I've always been more of an Eheim man, until a friend told me about the Fx6. My complaint with Eheim was the fact that it can be a pain to prime, and I didn't want to go through that again, so I took the plunge and bought the Fx6 for my newly setup 125 gallon tank. When the package arrived I was shocked at the size of this thing. It reminded me of a canister vacuum cleaner. After a quick unboxing, and cursory accounting of parts, I began the process of assembling the filter at 5:15 PM. At 5:45 PM, I turned it on, watched it cycle, and then settle down to a almost silent hum. I didn't have to do anything but watch. It did it all. No sucking on the intake to get it to prime, no water splashing everywhere because you couldn't get the hose on fast enough, and no fuss at all. How nice is that? The outtake, while very strong, was easily adjustable, so the stream pointed upward, and away from the middle of the tank. You cannot hear one little drop of splashing water. I will be keeping Discus and they don't like hurricane water. Like most new tanks mine was quite cloudy, and had been for a couple of days before I started the filter. Overnight the cloudiness completely disappeared and the water is almost crystal clear. Bottom line: while expensive it's one of those "you get what you pay for" situations and I consider this easy to assemble, simple to start, highly efficient filter getting what I paid for. I recommend it most heartily for the reasons I have mentioned. Incredibly easy to assemble and starting is a matter of plugging it in. Very quiet and by all appearances very, very efficient. If you have one of these there is no need whatsoever to use an additional filter on a large-100-200 gallon tank. This big boy will take care of everything for you.

We bought this canister filter for our aquatic turtle in Dec 2020 and it was the best investment ever!! It's quiet and works non stop cleaning her 100 gal tank! Woke up this morning to her tank looking horribly bad! The water, which is usually clear to clear with a slight green tint to it, was a dark muddy mess and we couldn't even see our 11 inch turtle, Crush! We thought our fantastic filter had conked out, but once we drained the water we could see what had happened... our silly girl had knocked the input tube apart and had caused a big air bubble in the filter, and subsequently the filter dumped a ton of muck back into her tank trying to fix the issue. So we did a cleaning of the tank and hooked the filter back up and everything is running smoothly & quietly just as it should!!! We love this filter... it just needs to be taken apart and cleaned every 6 months, witch we do like clockwork! We had tried other filters from our local pet store before getting the Fluval FX6 and they were all a waste of time and money! I can't recommend the Fluval FX6 enough!

Worth the investment if you want the best filter money can buy! We have slider turtles in big indoor ponds and pond cleaning day has always been a huge headache (and backache!!) Until I finally decided to save up for one of these. Now we have them on every pond and they make everyone's life so much easier! The turts get freaked out when we have to put them in a separate area while we clean their dirty turtle condos😆 but where it used to be an every other week endeavor, now we can go months before we have to dismantle everything and stress out our shelled children! And in our case, the biomedia has only needed to be replaced once a year. I've heard you can even find off brand replacement biomedia as long as you go with a reputable company but I cant speak on that, we've only used fluval. SO....If you are a water critter parent and you are able to save up, or if you are rich and $400 is nothing to you(must be nice😏) don't hesitate on this powerhouse of a filter. I'll never use anything else, we are a Fluval family for life! 🐢🐢🐢

Update- The units motor pulsated and is pulsating and began to die after less than seven months. Contacting Fluval is almost impossible as their hours are only 10 to 4 Monday through Friday and they only offer email customer service. And the email process is seriously slow. No voicemail available and no weekend call hours available. Makes it very difficult for those who work Monday through Friday during the hours of 10 to 4. I plan to look at a different brand. This is THE filter to purchase. I have a 90 gallon tank that had a Aquatop CF400UV which circulates 360 gph and worked well. I was looking for something to handle the load with 5 medium fish (2 black Oscars, black ghost knife fish, false tiger, and a Rafael -all will be transferred to a 150 soon). The unit is whisper quiet, easy to set up, and easy to maintain. It’s been running for 4 weeks now and I replaced the carbon pad per the maintenance schedule. Super easy. The flow is adjustable per Fluval at no less than 50% without any adverse effects to the motor. I began with 75% and then moved to full output. One output faces the surface for oxygen agitation and the other is aimed at the bottom of the glass. Works great. Water is crystal clear! I used the media that came with it except I replaced the bio rings with Seachem Matrix and added pouches of Purigen and Phosguard. Suggestions: To avoid water on the interior bottom of your tank stand, place the canister in a plastic storage tub as sold at big boxes (clear plastic tray 6”high by 24” wide) and place two smaller tubs (shoebox size) on the right and left sides if you have the room. When servicing, this allows me to remove the two valves and lay them in a side tubs and slide the tub with the canister out from under the tank stand. This keeps my stand dry. Second, as noted in another review, Flowtamer makes a spray bar specifically for the FX. Of Course you can make one yourself. Third, it does not come with a UV sterilizer but one can be added as I am considering an in-line unit.

Fluval FX6 ha risolto i mimei problemi di poca dimensione del filtro nell'acquario. Acqua pulita, cristallina e niente più alghe. Le vecchie stanno sparendo e il fondo non ha più residui. Potente e silenzioso. Comodamente riposto nei vani di un Juwel Rio 450 (o Vision 450). Comodo da pulire. Qualche adattamento da fare nella parte superiore dell'acquario (lo ho preferito a fare fori nel vetro). I tubi possono (devono) essere migliorati come estetica e qualità del tubo da parte del produttore, sono grandi, ma gli attacchi rapidi sono ottimi e dotati dei rubinetti di chiusura e apertura. Nulla che dire ottimo investimento. La pulizia del filtro è facile, finalmente niente bagnato o stracci ovunque. Speriamo duri nel tempo.

Really disappointed that I have to give this one star after all the research and reviews I followed before finally ordering. Set it up correctly however it just did not perform, very poor flow and vibration felt on the unit. Tried and tried again but still the same so it got packed up and sent back for a refund. I’ve just been unlucky to receive a bad unit I guess. Already have seven other canister filters of different manufacturers and sizes running on my aquariums so I was not expecting this when investing in what is supposed to be a very reliable unit.

Funciona perfectamente, gran potencia sin ruidos apreciables. Una buena compra …

I know a lot of people said it’s an overkill for 55 gallon, but I still decided to have this one instead of FX4, because both of them take up the same space, it’s just FX is taller. Also, not that much more expensive. Before the purchase, I am worried that the water flow would be too powerful for the tank. It turns out it’s perfect as the water flow can be adjusted and reduced! I am so glad I made this choice! It makes my tank so clean, and it’s so quiet but powerful! Love it. Highly recommend

Installed this on a 600L setup and it’s been flawless. Prime it once, plug it in, and it just runs. Flow rate’s strong without blasting the fish, and the multi-stage filtration keeps water crystal clear. Handles heavy bioloads—ideal for cichlids, goldfish, or planted tanks with messy eaters. Maintenance is straightforward: shut-off valves, easy-lift baskets, and a purge valve for draining without lifting the whole unit. I’ve cleaned it out monthly and it’s never clogged or dropped flow. ⚙️ Specs & Features Flow Rate: 3500 L/h Tank Size: Up to 1500L Media Baskets: 6-stage filtration (mechanical, chemical, biological) Footprint: Compact for the power—fits under most cabinets Smart Pump Tech: Auto air purge every 24h to maintain efficiency Drain Valve: Bottom purge for easy water changes 🔇 Noise & Build Runs near silent—just a low hum if you’re close. No vibration, no rattle. Build quality’s solid—thick casing, tight seals, and heavy-duty clamps. Feels like pro-grade kit, not hobby gear. 👍 Pros ✅ Massive flow—handles big tanks with ease ✅ Multi-stage filtration—crystal clear results ✅ Easy maintenance—quick access and purge valve ✅ Quiet operation—ideal for living spaces ✅ Durable build—long-term reliability 👎 Cons ❌ Pricey—but worth it for serious setups ❌ Large footprint—check cabinet space ❌ No media included—buy your own to customise ❌ Heavy when full—drain before moving 🧭 Personal Verdict If you’re running a big tank and want gear that just works, the FX6 is a beast. I’ve used it for months—no leaks, no noise, no stress. It’s not cheap, but it’s built to last and keeps water spotless. Ideal for anyone who wants pro-level filtration without babysitting the kit.