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Fluval U2 Internal Filter Review

The Fluval brand (by Hagen) has become one of the most well known names amongst fish keepers and it is for good reason. For many years now they have provided one of the highest, if not the highest level of quality when it comes to aquariums, filters and other accessories fish keepers have come to know over time. They have expanded their range over time but the quality has stayed the same.

Fluval have a range of Internal and yet powerful filters suitable for smaller aquariums and those slightly larger ones with low levels of livestock. In this post I am going to review the Fluval U2 Internal Filter suitable for aquariums of up to 110L. With an output of 400L per hour it certainly packs some punch, in fact if your aquarium is smaller than 45L then is much too powerful.

Key features of the Fluval U2 Internal Filter:

  • Multi-tray media system
  • Sleek design
  • Powerful water flow rate
  • Suitable for aquariums between 45L to 110L
  • Output: 400L per hour
  • Adjustable flow control (3 settings)
  • Suitable for freshwater and saltwater set ups
  • Dimensions: 10 x 9 x 20cm – 4 x 3.5 x 8inches

With it’s powerful flow it helps circulate water around the aquarium and agitate the water surface to allow oxygen to enter the water. You can adjust the flow if your fish or livestock prefer slower moving water using the nozzle heads provided with purchase. One other major plus point for this filter and indeed all the other Fluval filters I have used (U2, 305, 306) is that it is absolutely silent. Even if I stand next to my fish tank I can’t hear it. It is one of the biggest worries that fish keepers new and experienced have but rest assured this is very much silent.

It can be used as a lone filter or with other filters for extra filtration and water movement like I use it. Mine has been running for about 7 months now and it is still as strong as ever and continues to be completely silent. It has 3-stage filtration with foams, BioMax rings and Carbon included as standard. You can find replacements for these relatively easily either from your LFS or online.

The only downside to this filter (and I am clutching at straws here) is it can be fiddly to take out and clean. There is a vertical “platform” that you stick to aquarium suing suction cups and the filter itself is attached to this. But when it comes to removing the filter for cleaning I often find the “platform” comes off and it is not all that easy to attach the filter to it either. Regular cleaning is important to extend the life expectancy of your Fluval U2.

Fluval products are usually on the more expensive side if compared to products in their range and this is no different. This U2 model can be bought in the region of £30 here in the UK, which compared to filters of a similar size is slightly more expensive. It is however, extremely reliable and durable and has multi-stage filtration which some of the cheaper alternatives lack. It is important to remember that cleaning your filter regularly will give you the best results.


This is the filter for you if your aquarium sits somewhere between 45L-110L. It is well built and shows the quality and reliability we have come to associate with Fluval products. At 20cm high it can be a bit tall if your aquarium is on the shorter side but it’s relatively slim so won’t take up much surface area at all. It is a little difficult to take out and put back in the aquarium when cleaning it but once it becomes part of your fish keeping routine you will no sooner get used to it. It can be considered a bit pricey at around £30 but it is a product that will last with care and maintenance.