Enjoy improved water clarity in your aquatic environment with this underwater filter. Featuring a 3-stage filtration system with BIOMAX, the filter collects debris and removes impurities to ensure water quality. The 3-way flow rate adjusts for output flexibility, while the flip-top design makes cleaning simple.

Overall rating:

4.5

(13 reviews) 13

12 of 13(92%)customers recommend this product.

Reviews for Fluval(r) Underwater Filter

Review 1 for Fluval(r) Underwater Filter

Overall rating

5 / 5 13 reviews

Amazed

May 6, 2013

by Maxtor

fromMilford, DE

What is your gender?M

How many pets do you have?5 or more

How often do you shop at PetSmart?Monthly

Performance

5 / 5 13 reviews

Quality

5 / 5 13 reviews

Ease of Use

5 / 5 13 reviews

Was looking for a filter for a new 29gal tank setup. Looked at reviews for the Fluval U3 and thought this might be a good choice. Purchased and set up in my existing 20gal to let it cycle there before starting the new tank. My existing 20 had a Whisper 20 in it which I thought did a good job.....boy was I wrong! The U3 had the water crystal clear in no time. Puts my old one to shame. Will definitely be purchasing a U2 to replace that old filter!!! U3 is simple to begin using and feels well built. Filter media changes are going to be super easy. AWESOME AWESOME AWESOME!!!!

Pros: works great, easy to install

0points

0of 0voted this as helpful.

Review 2 for Fluval(r) Underwater Filter

Overall rating

5 / 5 13 reviews

Crystal clear

April 14, 2013

by mestrass

fromchicago suburbs

What is your gender?F

How many pets do you have?5 or more

How often do you shop at PetSmart?Monthly

Performance

5 / 5 13 reviews

Quality

5 / 5 13 reviews

Ease of Use

5 / 5 13 reviews

I started a 55 gallon premolded pond with quite a few messy goldfish. The tank went for about 4 days without a filter and got very cloudy. I knew the ammonia levels had to be elevated and there was alot of waste. Within 15 minutes of plugging in the filter, the water was already crystal clear and the flow is adjustable. It is easily hidden and absolutely silent.
For beginners, i cannot recommend a better, more affordable filter. Easy to set up and well worth the price. I have had aquariums my whole life and have spend much more on much less efficient equipment.

Pros: works great, easy to install, easy to clean

0points

0of 0voted this as helpful.

Review 3 for Fluval(r) Underwater Filter

Overall rating

5 / 5 13 reviews

Great filter!

March 7, 2013

by MSally88

fromVirginia

How often do you shop at PetSmart?Weekly

Great warranty! I use this in an African Leaf Fish tank and I love it.. it's much quieter than the typical filters that hang on the back of the tank and does a great job of circulating the enitre tank.

0points

0of 0voted this as helpful.

Review 4 for Fluval(r) Underwater Filter

Overall rating

2 / 5 13 reviews

Worked great... until it broke after 5 months.

February 3, 2013

by EnoughCats

fromFredericton, NB

What is your gender?F

How many pets do you have?5 or more

How often do you shop at PetSmart?Weekly

Performance

5 / 5 13 reviews

Quality

2 / 5 13 reviews

Ease of Use

4 / 5 13 reviews

I bought the U3 and was initially very impressed with it. I loved how quiet it was and that it would not burn out after a power outage because you didn't have to prime it. It did it's job of keeping the water clean and clear. On the downside it was quite bulky and took up a fair portion of my tank. My U3 broke after only 5 months of use. I maintained the unit well and changed media regularly. If it hadn't quit on me I would have given it 4 stars.

Pros: easy to clean

Cons: didn't work

+1point

1of 1voted this as helpful.

Review 5 for Fluval(r) Underwater Filter

Overall rating

4 / 5 13 reviews

Surge Protector a MUST...

December 28, 2012

by AnmlLvr13

fromNorristown, PA

What is your gender?F

How many pets do you have?5 or more

How often do you shop at PetSmart?Weekly

Performance

4 / 5 13 reviews

Quality

3 / 5 13 reviews

Ease of Use

4 / 5 13 reviews

I recently acquired two turtles and this filter has been amazing. Easy to use, quite and the water was crystal clear... until a brief power outage one night. The filter's motor is shot. I would still recommend this filter to anyone, as long as a surge protector is used.

Pros: easy to install, easy to clean

+2points

2of 2voted this as helpful.

Review 6 for Fluval(r) Underwater Filter

Overall rating

5 / 5 13 reviews

The U2 is just amazing.

December 25, 2012

by AppleGeek

fromNorfolk Virginia

What is your gender?M

How many pets do you have?5 or more

How often do you shop at PetSmart?Weekly

Performance

5 / 5 13 reviews

Quality

5 / 5 13 reviews

Ease of Use

5 / 5 13 reviews

I purchased a 10 gallon kit 6 months ago that came with another HOB filter that was so loud, and unreliable. I picked up a U2 about 2 months ago, and I was amazed, a few hours after setting it up and putting it in my tank, it cleared the water and it made everything look great in my tank. about a week ago, I removed one of the carbon pads, and put a filter bag with Seachem Purigen in it, it cleared the water even more, and now it looks like my fish are floating on air. I love it.

Pros: easy to clean, works great, easy to install

+3points

3of 3voted this as helpful.

Review 7 for Fluval(r) Underwater Filter

Overall rating

5 / 5 13 reviews

Awesome Filter

May 24, 2012

by Lunarcat13

fromCape May, New Jersey

What is your gender?F

How many pets do you have?5 or more

How often do you shop at PetSmart?Weekly

We have a 60 gallon tank with 2 turtles and quite a few fish. We got the U4 filter when we upgraded from a smaller tank to this one. It was recommended to me by someone so i decided to try it. Its quiet, powerful and can take a beating basically. We fell behind in our cleaning duties and the filter still kept the water fairly clear and after the cleaning when we stirred up all the stuff on the bottom and out of the plants with in 30 minutes tops the water was crystal clear again like we just put the tank together on the first day. I would recommend this to anyone with fish and/or aquatic reptiles! In fact I'm thinking about getting the U3 for our smaller tank to replace the one we have on there now.

+3points

3of 3voted this as helpful.

Review 8 for Fluval(r) Underwater Filter

Overall rating

3 / 5 13 reviews

Good But......

April 2, 2012

by John60

fromSt. Charles, Mo

What is your gender?M

How many pets do you have?5 or more

How often do you shop at PetSmart?Weekly

A good filter overall but the ceramic rings they give you are enough to fill the cage only half way. For the price you pay for the filter.....need I say? Sometimes you don't get what you pay for.

-1point

4of 9voted this as helpful.

Review 9 for Fluval(r) Underwater Filter

Overall rating

5 / 5 13 reviews

Quiet, and clean

March 13, 2012

by rlar422

fromCT

What is your gender?F

How many pets do you have?5 or more

How often do you shop at PetSmart?A few times a year

I have two of Fluval underwater filters, the U3 in my 29 gallon tank and the U1 in my 10 gallon tank, and I love them! They are so quiet and do an excellent job keeping the water clean. My U3 I have towards on side of my tank with it on the top spout on at an angle so it pushes the feces from my large pleco to be sucked into the filter. I have the U1 at the top with the air setting on, which is quiet as well and it keeps the tank aerated and clean! I love them!

+5points

5of 5voted this as helpful.

Review 10 for Fluval(r) Underwater Filter

Overall rating

5 / 5 13 reviews

Fantastic, QUIET filter

February 15, 2012

by Trace0306

fromSoutheastern, CT

What is your gender?F

How many pets do you have?5 or more

How often do you shop at PetSmart?Weekly

Thank goodness for great online reviews, because that's how we came to find this filter. We had a Marineland Penguin BioWheel that spontaneously stopped working after 2ish months. We got this Fluval U3 filter (29 gal tank) and installed it (5 min max!), within a couple hours, the tank looked as if we hadn't had a dead filter for a week, and the next morning, the water is completely clear. We use the airation option, and it doesn't sound like a running waterfall like the BioWheel. It'll take some time to see how it works out, but I have much higher hopes for this filter than the last.

+2points

2of 2voted this as helpful.

Review 11 for Fluval(r) Underwater Filter

Overall rating

5 / 5 13 reviews

The most amazing thing ever!

January 14, 2012

by Lina1234

fromTexas

What is your gender?F

How many pets do you have?5 or more

How often do you shop at PetSmart?Monthly

I bought the Fluval u1 for my ten gallon tank and it is amazing. The filter part is wonderful but what i love is that it is 100% quiet. In my starter kit i had a top fin filter and it was horrible. It kept vibrating and the hum was so annoying. It was in my room so it had to be dead silent. I did some research and i found this. I hooked it up ten minutes ago and i cant even hear it. I had to stick my finger in front of it to see if it was on. If you want a quiet filter, i highly recommend this. It's worth the money!!! Love it!

+5points

5of 5voted this as helpful.

Review 12 for Fluval(r) Underwater Filter

Overall rating

5 / 5 13 reviews

Fantastic Filter!

March 15, 2011

by Abernathy

fromPortland, OR

What is your gender?F

How many pets do you have?5 or more

How often do you shop at PetSmart?Monthly

Performance

5 / 5 13 reviews

Quality

5 / 5 13 reviews

Ease of Use

5 / 5 13 reviews

I purchased this filter when I set up my 46 gallon tank. It's really easy to set up and to use, and I love how it has the 3 different flow settings. My fish seem to prefer the water flowing across the surface, with bubbles, but during feeding, I change the flow to the middle. Just turn a dial. Changing the foam and everything inside is really, really easy. The filter also provides a hiding place for my upside-down catfish, and occasionally a tiger barb or a gourami will hang out under it too. Overall, FABULOUS product!

Pros: easy to clean, easy to install, works great

+6points

6of 6voted this as helpful.

Review 13 for Fluval(r) Underwater Filter

Overall rating

5 / 5 13 reviews

Found a winner!

March 15, 2011

by jessicabc

fromBC, Canada

What is your gender?F

How many pets do you have?4

How often do you shop at PetSmart?Monthly

Performance

5 / 5 13 reviews

Quality

5 / 5 13 reviews

Ease of Use

4 / 5 13 reviews

I'm so happy I decided to get this filter. I went through 3 other HOB ones before it, they were all way too noisy (and one was too big to even fit under my aquarium's hood). This one is super quiet. I haven't decided if I'll use the venturi valve for oxygenating the water or not, the bubbles are pretty quiet though so I'll give it a try. My aquarium is in my room so it definitely needs to be quiet. It took a little fiddling to get the level of the filter and the valve just right for the small amount of bubbles, which isn't a big deal, just need to find the right balance for what you want.

I got the U2 for my 23 gallon tank and I think it should be enough filtration. I was going to get the U3 but the size definitely put me off. The size of the U2 is fine though, it isn't too bulky and doesn't hog too much space (I have it in one corner of the tank just below the surface).

It was pretty easy to set up and looks like changing the filter bits will be easy enough as well. Doesn't seem complicated to me.

I really recommend this filter. Forget AquaClear.

Pros: easy to clean, easy to install, works great

+5points

6of 7voted this as helpful.