Fluval U4 Underwater Filter, Freshwater and Saltwater Aquarium Filter, A480,Black

__________________________________________________________________________UPDATED 7/26/12-- see bottom part of entry-- upgrade from 3 to 5 stars__________________________________________________________________________Original review June 2012:I'm writing a long review because I found it helpful to hear others' experience specifically with turtles. They are a little different than fish when it comes to what works.I have a painted turtle, about 5-6 inches long right now. We have an algae eater too who helps keep the tank clean (we call it a sucker fish, not sure what its real name is). We also periodically add small minnows and goldfish to entertain the turtle and for food if we forget to feed her or go on vacation. Since she's primarily a water turtle, her tank consists of mostly water with a few haul out spots.We just upgraded from a 20G tank to this one. Previously we've always used the Whisper Quiet filters with great success. People would rave about how clean the turtle tank was, and we could pretty much ignore it (don't worry about changing water, etc.) In the 20G tank we had the 20-40G Whisper Quiet in about 16G of water, no plants, a few submerged items, and a floating plastic "log" for basking. For the 50G, we added a few more submerged and surface items, but all are plastic or rocks, nothing living.Upgrading to the 50G tank (with about 40-42G water) posed a problem for me. All of the larger hang on back filters required the water level to be higher than I wanted, since the turtle needs some land, and I didn't want it climbing out. I tried rigging a few up-- the larger Tetra one worked very well, but I had to rig it inside of the tank, and it just took up too much room.I decided to try the underwater Fluval for two reasons-- never need to worry about water level, and because I'm not willing to invest in a canister filter.PROS:--silence. it's golden--ease of changing filter media (it's really simple, you can lift it up so you don't contaminate everything or spit junk back out)--will never dry out or burn out if you lose power and it restarts (since submerged)--ability to place where I like in the tank for optimal filtering and flow to stir things up--ability to change parts of filter at a time to preserve beneficial bacteria--foam pad separate from other pieces so you can rinse that and not everything--no splashing, so no hard water stains on side of tankCONS:--I want to love this filter and I hope it works long term. We used it in a tank that had been recently filled and set up, with the Tetra running for about a week. Initially this worked really well, but about a week into it, the water turned nasty green. First off, TURTLES ARE DIRTY. By nature I don't think this filter accomodates that. I'm holding off judgement since it sometimes takes a while to get things right when you set up a new tank, as it happened before with other filters too at times. However, in this case, I think it's because of a lack of active carbon in the filter. There is just a tiny bit there, and in my experience (6 years with this turtle), the active carbon is ESSENTIAL to keeping them from getting stinky and gross. I decided to remove the bio pellets from the middle part (step 3) since I never had them before in my tanks anyway, and instead fill that space with one of the tetra filters filled with activated carbon. It's been about 10 hours. The nastiness is gone and the tank looks much better. There still seem to be a lot of particles in the water, but I am continuing to work on that-- not sure if I can blame it on the filter at this time. I will keep adjusting, because I think this filter is worth figuring out how to make it work for turtles.I gave it three stars because it advertises that it can be used for my purpose, but I don't think it comes through with the media it uses. I also think their media replacements are expensive relative to other filters (which is especially frustrating when they aren't even working for me). However, if the makeshift adjustment of using other carbon filters inside the third chamber is effective, I would upgrade to 4 stars. If I get to perfectly crystal clear water without the need to pay attention to the tank every week (yes, it's possible with some cheap filters), I'd go to 5 stars. I ask a lot from my filters!___________________________________________UPDATE 7/26/12This definitely deserved the upgrade to five stars. I had to leave for three weeks after adding the Tetra carbon filter to the center in place of the bio pellets, so I filled it with a bunch of minnows for her to eat over time, then came home to a tank that was still crystal clear after 24 days. (Trust me, I was almost afraid to look at the tank when I returned for fear of how gross it might be.) A few minnows were still swimming around happily too. I went ahead and swapped out the carbon filter, but it looks like I can simply wash out the outer sponge and pathetic carbon insert supplied with it periodically and replace the Tetra carbon insert in the center chamber monthly. I still don't like that I had to adjust it, but I don't think there's a great product out there for turtles, and this is working VERY well. Plus, I am now purchasing the cheaper Tetra filters, so my ongoing costs will be less.If you go this route, it does seem like a very tight fit to fold over the Tetra filter and slip it in the middle chamber, so don't be shy. Just wiggle it as you push it in and be gentle.All that remains to be seen is longevity, but for now I am one happy consumer!

I added the U1 to my 20 gallon tank that already had a 20 gallon filter. I wanted some flow, and extra filtration since I have a few more fish than I should.The sponge covers all inlets, so my Kuhli Loaches and shrimp aren't at risk of being sucked in, which is extremely nice. Any other filter or pump I've used required me to superglue sponges or screens to the inlets. I also love that the sponge is easily removeable via the lid, so I can pull it out and clean it without moving the filter. It also has a removeable piece in the center that I removed and replaced with a media bag full of Zeolite and Carbon blend with some compressed peat for acidity.Mounting the filter was the only downside I had with it, but because of the easily removeable sponge I'm not knocking off a star for it. The U2 and higher models have a bracket, the U1 just has 3 easily removeable suction cups (not a good thing) so once you stick it on the glass, if you even try to move it the tiniest bit to position it just right the suction cups disconnect from the unit and stay stuck on the glass, forcing you to pry them off, pull out the filter, reattach the suction cups, then reposition it again. That said, it stays put, its fairly small, and looks nice.For a filter that attaches to nothing but the wall, it's very quiet. Much more so than the two cheaper units I used. Obviously a HOB will be quieter since it isn't attached to the entire tank turning your tank into a giant vibrating subwoofer, but for something that DOES transmit all of its vibrations straight into the tank its very quiet. My Marina HOB is quieter and the U1 does make a very faint grinding noise, but I can only hear it right next to the tank and 5 feet away it is inaudible.Filtration is great as well. I use it as a second filter, since my HOB is stuffed full of loads of different media so the flow rate is lower, so this serves primarily as a bio-filter to reduce ammonia. For that purpose it does fantastic, and the small media bag in the middle for some extra filtration is nice too. The flow is the best part here though, it keeps my substrate crystal clean and any gunk that gets kicked up by the loaches or cories immediately gets swept into the current and sucked up by the filters. If you're using this as your only filter, definitely add some zeolite and carbon to the middle of it.All said, it's a fantastic filter and I honestly wish I just had one U2 for my 20gal rather than two separate filters.

I have a planted 40 Gal Long (48 x 13 x 17) and needed a replacement for an older Fluval 202 canister filter. I really didn't want a new canister filter and a biowheel wasn't going to work for me due to the plants. There are HOB filters that would have worked out but in my experience they're just as clunky and hard to clean as a full canister. So the U3 seemed like the perfect compromise; no priming, no tubing, just dip and drive!This filter appears very easy to clean and maintain. I love the central 'spray bar' between the two main outlets. The flow adjustment knob makes it easy to find the perfect balance between the three outlets, very clever and useful feature. I also appreciate that the trays are vertically aligned, no stacking or digging for trays.My only gripe with the U3 is that it is quite small for the job it claims to do. It claims to be good for up to 40 Gal but truthfully 40 Gal may be too much for this filter. I suppose if you had a stock tank with no plants and minimal population it would be fine. But most people may want to consider moving up to the U4.I myself am considering purchasing a second U3. The output is strong enough to provide all of the circulation I need meaning I can remove my power heads. They fit so nicely in the corners of the tank that I should end up with a really nice clean look. Also I think even two of these little submersible filters will still be easier to clean and maintain than one big canister filter.

I love this thing , great price, great build quality, doesn’t make any noise when properly submerged, I like the design and color , it helps a lot to keep the home of 3 female red eared sliders clean