Fluval Aquarium Underwater Filter

By Fluval
Rated 3.7162 out of 5 stars
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Fluval Aquarium Underwater Filter, 24-40 gal slide 1 of 2
Slide 1 of 2
Fluval Aquarium Underwater Filter, 24-40 gal slide 1 of 2
Size
$38.99Chewy Price
List:
$79.99Chewy Price
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$41.00
(51%)
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Frequently Bought Together
Rated 3.7162 out of 5 stars
74
$38.99Chewy Price
Frequently Bought Together
Rated 3 out of 5 stars
4
$5.49Chewy Price
Frequently Bought Together
Rated 4.5 out of 5 stars
2
$2.92Chewy Price
Total Price: $0.00

About This Item

  • Optimal water filtration system for aquariums that ensures proper oxygenation for clear water and a healthy environment.
  • Fine foam pad traps small debris while bio-foam captures larger debris and nitrifying bacteria.
  • Adjustable 3-way flow control—top output for circulation and oxygenation, integrated spray bar for a gentle even flow, and bottom output for deepwater agitation.
  • Convenient flip-top lid allows for quick and easy access to filter cartridge for maintenance or replacement.
  • Ideal for freshwater, saltwater and reptile environments.
Play Video: Learn More About Fluval From Our Team of Experts
Learn More About Fluval From Our Team of Experts

Compatible Products

Ensure your system runs smoothly with Fluval accessories.

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Customer Rating
Rated 3.7162 out of 5 stars
74
Rated 3.7423 out of 5 stars
97
Rated 4.2588 out of 5 stars
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Price
$38.99Chewy Price
$41.23Chewy Price
$25.27Chewy Price
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$24.99Chewy Price
Fish TypeTropical Freshwater, Marine FishTropical Freshwater, Marine FishTropical Freshwater, Betta, Cichlid, GoldfishTropical Freshwater, Marine FishTropical Freshwater
Aquarium TypeFreshwater, SaltwaterFreshwater, SaltwaterFreshwater, SaltwaterFreshwater, SaltwaterFreshwater
MaterialPlasticPlasticPlasticPlasticPlastic
Capacity (Max)N/AN/AN/AN/AN/A

Questions & Answers

22 Customer Questions

What size do i get i have a 75 gallon tank
Answer by Chewy • Sep 28, 2017
The largest size we carry would be the U4, which is used for tanks that hold between 34-65 gallons.
I just installed my U3 in a turtle tank. People were bragging about it being very quiet. Mine is not. Is this filter supposed to be soundless? I'm new to this and I don't know anything about filters. Somebody gifted my 4 year old with a baby turtle and I'm trying to do my best to take care of it.
Answer by Chewy • Nov 27, 2017
Typically the filter will make noise if the water level is below the filter. We encourage pet parents to fill the tank 2 to 3 inches above the filter to prevent this.
Can I use this for my Betta fish, how fast is the flow?
Answer by Chewy • Jan 10, 2018
This Filter allows for adjustable flow and will be suitable for a tank with a Betta.
What size is best recommended for a 75 gallon tank? Thank you!
Answer by Chewy • Feb 04, 2018
The U1 is suitable for up to 15 gallon tanks, the U2 is for 12-30 gallon tanks, the U3 is for 24-40 gallon tanks and the U4 is perfect for 34-65 gallon aquariums. At this time this model does not have an option for a 75 gallon tank.

ReviewsWrite a Review

3.7
Rated 3.7162 out of 5 stars
74 Reviews
77%
Would recommend to a friend
1
14.8649
15%
2
13.5135
14%
3
9.4595
9%
4
9.4595
9%
5
52.7027
53%

74 Customer Reviews

Rated 1 out of 5 stars
By Food on Mar 30, 2022

stopped working

Stopped working 3 months in , wouldn’t recommend-I cleaned it out every week as recommended religiously the way the instructions state -and that seems to be the census I’m seeing on these reviews

Rated 2 out of 5 stars
By Rebecca on Mar 9, 2022

2 months in

And it just stopped working for NO reason. One day was fine the next nothing. Would not spend the amount for 2 months working

Rated 5 out of 5 stars
By Scruffle on Apr 2, 2022

Super Quiet

Wish I had bought this filter years ago, very a quiet, the fish are very happy.

Rated 4 out of 5 stars
By BuffaloFrank on Nov 7, 2021

Nice product but cheap impeller blades break within a year of purchase

Great product. Except the green spinning blades on the impeller assembly. Fluval won't mail you just the 25cent replacement plastic. They sell the full magnetic impeller assembly for $17. A new filter costs ya $37. Do the math - Fluval customer service sucks and they only care about selling more. Not helping their knowlegable customers with a quick easy repair option ...

Rated 2 out of 5 stars
By FishMom22 on Nov 8, 2021

Not a Great Product IMO

This is also my second one of these filters. The first one didnt work when I received it, so Chewy replaced it at no charge (their service is top notch). The second one just died after only one year of use. Literally just stopped working. What is happening with Fluval? My first Fluval filter lasted for years. Kind of mad about it. All done with the brand.

Rated 1 out of 5 stars
By Lexi on Sep 25, 2021

Quit working within the week.

I was happy with this filter at first, as it is easy to assemble and looks good, doesn't take up much space, was very quiet and worked well. However, within the first 7 days of use, the filter started making a very loud noise and foaming up the water/making the water extremely dirty. Cleaning and maintenance to the filter does not fix this issue. I've had it only about two weeks and it is completely unusable. Ultimately would not recommend for more than a couple day holdover.

Rated 2 out of 5 stars
By size on Feb 25, 2022

I don’t get it!

It’s very confusing. The directions really don’t help either.

Rated 4 out of 5 stars
By Sparky on Jan 22, 2022

Impressive filter

I would recommend this filter for anyone. Fluval is top notch in my opinion

Rated 3 out of 5 stars
By QuietWater on Sep 4, 2021

Possibly Need more Help on this Filter

So, yeah, I might need more help on this filter. Not a lot of water pressure/flow coming out. Kinda easy to assemble. No idea how much the replacements are going to cost on the filters, and the tank is still kinda cloudy. Maybe I need to give it the rest of the week, but I have a 20 gallon tank, and this is for a 30 gallon. Maybe I'm missing something.

Rated 2 out of 5 stars
By Bummed on Aug 27, 2021

Works well if you only need it for one year

I really loved this filter but this is the second one that has failed right around the 1-year mark. I’m going to have to try something else.