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Fluval U2 Underwater Filter – Designed for Freshwater and Saltwater Aquariums, Also Ideal for Terrariums and Turtle Tanks

4.1 4.1 out of 5 stars 9,579 ratings

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U2

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About this item

  • Use as a primary filter for smaller aquariums, or supplementary filter for larger aquariums
  • Sleek design with easy grip water control panel and redesigned media cartridge to trap more debris
  • Convenient flip-top lid allows for quick and easy access to filter cartridge for maintenance or replacement
  • Position horizontally for shallow tanks, larger tanks with low water levels, or to create a decorative waterfall feature or vertically against aquarium wall to create currents or customized flow patterns
  • Designed for freshwater, saltwater and reptile environments up to 30 gallons

Customer ratings by feature

Noise level
4.2 4.2
Sheerness
4.2 4.2
Suction power
4.0 4.0
Easy to clean
3.9 3.9

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From the manufacturer

Fluval Underwater Filter

  • Fluval U Series Underwater Filters provide complete and efficient 3-stage filtration, including BIOMAX biological filtering (U2, U3 and U4 models), to create superior aquarium water quality.
  • The complete line, consisting of Fluval U1, U2, U3 and U4 Underwater Filters, includes many practical and versatile features that make them ideal for application in fresh, marine and reptile environments.
  • Fluval U series filters provide the option of setting the flow output in 3 different positions, a key benchmark in underwater filtration. The Adjustable 3-Way Flow Control feature (available in the Fluval U2, U3 and U4 models) lets you position the water flow output to meet your specific needs. The Top Output setting provides maximum circulation and oxygenation, the Integrated Spray Bar setting provides a gentle, even flow for planted aquariums, and the Bottom Output setting is for deepwater agitation.

Features

  • Fluval U Filters also include a convenient flip-top lid that allows quick and easy access to the filter cartridge for maintenance or replacement.
  • In addition, Fluval U Filters offer installation versatility: they can be installed vertically against the aquarium wall to create currents or customized flow patterns; or they can be placed horizontally in shallow water tanks or to create decorative features such as waterfalls.

Product guides and documents

Product details

  • Is Discontinued By Manufacturer ‏ : ‎ No
  • Product Dimensions ‏ : ‎ 3.9 x 5 x 8.8 inches; 1.7 Pounds
  • Item model number ‏ : ‎ A470
  • Department ‏ : ‎ men, women
  • Date First Available ‏ : ‎ August 19, 2004
  • Manufacturer ‏ : ‎ Rolf C. Hagen (USA) Corp.
  • ASIN ‏ : ‎ B001Q1HPGE
  • Country of Origin ‏ : ‎ Italy
  • Customer Reviews:
    4.1 4.1 out of 5 stars 9,579 ratings

Looking for specific info?

Product Description

Fluval U2 Underwater Filter is ideal for use in all aquarium or reptile environments. Use the underwater filter as a primary filter in smaller aquariums or as a supplementary filter for larger aquariums. Fluval Underwater Filters with three-stage filtration are ideal for use in fresh, marine or reptile environments, and are also great for tanks with low water levels. Three-stage filtration with BioMax for superior aquarium water quality, flip-top access for quick and easy cartridge replacement, and three-way flow control make the new Fluval U Series the benchmark in underwater filtration. Stage 1 foam removes large particles. In stage 2, the poly/carbon cartridge traps fine debris, improves water clarity and removes impurities. In stage 3, BioMax provides optimal biological filtration efficiency.

For more fish tank accessories, check out other Fluval products including aquarium filters, aquarium heaters, aquarium air pumps, aquarium lights, aquarium rocks, aquarium thermometers, and aquarium stands. Fluval has a wide variety of products that are perfect for your pet fish to enjoy in any large fish tank, small fish tank, saltwater tank or freshwater tank. Fluval broke onto the aquatic scene in 1975 by introducing the world’s first 3-stage filter with synchronous motor technology – a breakthrough that is still applied in the industry today. Since then, Fluval has built a legacy around this pioneering spirit, relentlessly adapting in a changing world to launch innovative aquarium products that remain at the forefront of technology, and which set the bar in quality, style and functionality. Fluval’s mission is not just about building products that mimic the natural world, but inspiring aquarists of all skill levels to enjoy and respect the hobby for generations to come.

Important information

Directions

Follow individual packaging instructions.

Customer reviews

4.1 out of 5 stars
4.1 out of 5
9,579 global ratings

Customers say

Customers like the filtration of the water purification unit. For example, they mention the filter itself is fantastic and a very good underwater filter. That said, some disagree on quality, flow, cleanability, size, value, and power.

AI-generated from the text of customer reviews

246 customers mention199 positive47 negative

Customers like the noise level of the water purification unit. They say it is extremely quiet and powerful. Some customers also mention that it is submerged in the tank and cannot be heard at all.

"...For a filter that attaches to nothing but the wall, it's very quiet. Much more so than the two cheaper units I used...." Read more

"ProsExtremely quiet, i almost forget its running unless i look in the tank and see the water movement from it...." Read more

"...It is surprisingly quiet. You can adjust the output. Water can exit from the top, the middle, or the bottom of the unit...." Read more

"...Whisper quiet and just enough power to shoot the water gently across to the other side of the tank. I couldn't be happier...." Read more

225 customers mention180 positive45 negative

Customers like the filtration of the water purification unit. They mention that the filter itself is fantastic, the resulting filtration is great, and the filter action is great. Some mention that it is a very good underwater filter and that it has excellent filtration options. Overall, customers are happy with the filter and recommend it to others.

"...All said, it's a fantastic filter and I honestly wish I just had one U2 for my 20gal rather than two separate filters." Read more

"...Highly recommended. This could be the best internal filter system available in the hobby, in the humble opinion of this reviewer...." Read more

"...Flow is amazing still after 3 months of not cleaning. No clogs...." Read more

"...Excellent water filtration, great options for filter media, nice to have 3 options of water flow..." Read more

342 customers mention224 positive118 negative

Customers are mixed about the power of the water purification unit. Some mention that it works well, while others say that it only works intermittently and stops completely. The motor would sometimes quit for no apparent reason and wouldn't restart.

"...For that purpose it does fantastic, and the small media bag in the middle for some extra filtration is nice too...." Read more

"...: Submersible design that could sit at the bottom of the pond, low enough wattage to run from a battery pack..." Read more

"...It was great for almost a year but it randomly started having issues staying on...." Read more

"Did great while it was working. Kept my 20 gallon guppy tank fairly clear, though the water output came out pretty strong...." Read more

215 customers mention143 positive72 negative

Customers are mixed about the cleanability of the water purification unit. Some mention that it does an amazing job keeping the tank clean and clear, while others say that it releases an crazy amount of debris back into the tank. The filter takes up more room inside and is more of a hassel to clean than hob filters. It does need regular cleaning, but this is unsurprising in the water treatment industry.

"...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..." Read more

"...pond all winter, and it handles sediment, decaying worms, and algae without complaint...." Read more

"...ConsTakes up more room inside.More of a hassel to clean than hob filters like the aquaclear...." Read more

"...All in all, a tidy, complete filter system.Disadvantages? It takes up a lot of space inside the tank...." Read more

166 customers mention75 positive91 negative

Customers are mixed about the quality of the water purification unit. Some mention that the pump is sufficiently strong, while others say that it breaks easily and is unreliable. The filter body is made of very sturdy plastic. However, some customers report that the unit stopped working completely after 6 weeks.

"...And, it gets used up very quickly. It is possible that you may be able to remove the biomax and put pelleted carbon in its place...." Read more

"...of this and the U3 have kept the pond naturally pretty and habitable for small fish...." Read more

"...First off, TURTLES ARE DIRTY. By nature I don't think this filter accomodates that...." Read more

"...Tadpoles are MESSY - but they are also tiny and delicate. You want a filter that moves enormous amounts of water in order to keep the tank clean...." Read more

133 customers mention87 positive46 negative

Customers are mixed about the value of the water purification unit. Some mention it's worth the purchase, reasonable priced for good quality, and a good filter for the price. However, others say that it seems a bit pricey, too costly to maintain, and the use of carbon increases the filter cost.

"...received a new impeller and installed it, I can tell this filter is very good, efficient and it’s a breeze to clean. I recommend and would buy again." Read more

"...No room for carbon like chemipureIts a solid 4, I am torn if i will keep or go back to the aquaclear...." Read more

"...Very quiet! It keeps the tank crystal clear. Without a doubt, worth the money!..." Read more

"...The replacement cartridges are not overly expensive and you can use your own mechanical media if you take the time to cut it to size...." Read more

99 customers mention49 positive50 negative

Customers are mixed about the flow of the water. Some mention that it's really good, surprisingly strong, and impressed by the water circulation. However, others say that it is not able to keep water flowing throughout the tank, and that it reduces flow within a few days.

"...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..." Read more

"...and completely clean the unit every five days or it almost completely stops pushing out water. Not a happy camper...." Read more

"...Phosphates, ammonia, nitrates, and pH have remained good, according to weekly tests...." Read more

"...this worked really well, but about a week into it, the water turned nasty green. First off, TURTLES ARE DIRTY...." Read more

87 customers mention35 positive52 negative

Customers are mixed about the size of the water purification unit. Some mention that it fits easily into the space where the previous filter had, and is fairly small. However, others say that it is kinda huge and takes up quite a bit of room.

"...Disadvantages? It takes up a lot of space inside the tank...." Read more

"...That said, it stays put, its fairly small, and looks nice...." Read more

"...One thing I don't like about this product is the space inside. Too small to put stuff in there but if you are creative enough, you know you can do "..." Read more

"...Doesnt take up excess room outside.Some have stated trouble starting but i havent had that issue.Cons..." Read more

Our Tadpoles *Love* It - I Posted a Photo
5 Stars
Our Tadpoles *Love* It - I Posted a Photo
The Fluval 2 Water Filter is designed to work in a variety of configurations. This makes it absolutely perfect for tadpole tanks. You can put it sideways, just beneath the surface of the water. This creates a long "basking area" that the tadpoles absolutely love, while at the same time keeping their tank clean.I had no idea the Water Filter would be so ideal when I bought it. Sure, I knew it had a great reputation as a water filter, and that it could create a gentle stream. That is of course the big challenge with tadpole tanks. Tadpoles are MESSY - but they are also tiny and delicate. You want a filter that moves enormous amounts of water in order to keep the tank clean. At the same time, you don't want industrial-strength jets of water blasting into their swimming area. Especially when tadpoles are just developing their little arms and legs, getting hit with that water blast could cause all sorts of damage.The Fluval 2 Water Filter is very easy to set up. You decide what kind of output stream you want, set the speed, and voila. You stick the whole thing into your tank and you're set. I put it in sideways figuring it would take up the least amount of swimming space that way. I was completely shocked when I came back a few hours later and found six of the little tadpoles had wriggled their way on top of it and were soundly sleeping there. At first, I was worried. Would a little limb get stuck somewhere? Would the soft buzzing bother them? But no, it almost seemed soothing. They actively wrestle with each other to get onto that spot and, even if others come and pile on top of them, they lay there contented. It is really cute to watch them. They're like a pile of kittens.The water in the tank is absolutely much cleaner with this running. It does the best one could hope for against the output of these industrious little baby frogs.Highly recommended for tadpoles. Just install it sideways, just below the surface, so the little tadpoles can rest on top of it. There's lots of photos and videos of this in action all through the SuttonMass site.Ask if you have any questions!
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