Fluval U3 Underwater Filter – Designed for Freshwater and Saltwater Aquariums, Also Ideal for Terrariums and Turtle Tanks

__________________________________________________________________________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!

The Fluval U3 Filter is a very good underwater filter. It does a good job keeping the water clean. There are adjustable flow vents so you can adjust how you want the water to flow, and you can change it anytime with a turn or a twist. It is very quiet underwater, and changing the filter and filter media is quick and easy. You can do it all underwater pretty much.The filter media can add up if you don't buy it at a good price. Amazon does have some good pricing and some items are sold in bulk which make it cheaper. The bio-media you only change half at a time so to not destroy the cycle you have in the tank. The filter sponge can be squeeze rinsed in a bucket of tank water to remove the yucky stuff at put back. The poly/carbon cartridge i the only think you need to replace completely. You can try to squeeze and rinse out the poly/carbon in a bucket of tank water to buy more time with it, but the poly and the carbon side may both be less effective over time. As mentioned, these things can be purchased in a bulk quantity on Amazon for a great price saving you a lot of money.I recommend the Fluval U3 Underwater Filter because it works great and is very quiet where you here nothing. No more crashing waterfall from your overhang filter. Amazon usually has one of the best prices on the Fluval filters. If you have Amazon Prime, the 2-day Free shipping is a huge money saving plus.

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

Not going to write a lengthy review. I'm just going to point out the reasons why I changed my rating from 5 stars to 1.-Filter only sucks in debris at the top half of the unit. A lot of debris just floats by the filter without getting sucked up. Weak suction.-Whenever you detach the filter from its frame that attaches to the aquarium, all the debris pours out from the bottom of the filter right into the tank. There should be a way to close all the suction holes during maintenance so the filth stays inside the filter.-After about 2 months of use, anytime I turn the filter off and on, the impeller does not start spinning. I have to detach the motor and spin the impeller with my finger in order to get it going. And yes, I have cleaned the impeller itself. The impeller cavity is also clean.-It's a pain in the rear to put the filter housing back into its frame. The housing does not want to lock into the frame. I do make sure the power cord is flat in its "cord trap", but this thing will fight you for a few minutes until it finally locks in. Good idea but not well executed.UPDATE: the more time i spend with this filter wanna be, the more I realize it's a complete failure. Look closely and you will see the tiniest of particles in your water floating by the filter like it has zero suction. Good luck with all that, Fluval!UPDATE # 2: Well the filter is now paper weight. The motor is almost dead. There is very little/non-existent water flow coming out no matter what I do. I have taken the media out, turned the flow knob in every which way and there is almost no output. The impeller is spinning but not that fast. And yes, the impeller has been cleaned along with the cavity it sit in.