Whilst there’s a huge selection of internal power filters available, both in the aquatic shops we frequent and even more online, there are one or two filter ranges that appear in most stores. The Fluval U series is one such range of products.
The Fluval U series ranges from the U1 for small tanks to the U4 for tanks up to 240 litres according to the manufacturer. My initial impression suggest that this filter is better suited to larger tanks as smaller models are very bulky. Other than that, the Fluval U series is packed with a lot of good features and is a good, sturdy filter.
There are numerous well-designed features on this filter: Firstly, the lid flips up to allow easy access to the filter media, avoiding the need for wet hands. There is a three-way outlet system allowing for water to exit via the bottom of the filter, a more evenly distributed flow along the side of the filter or via the top where there is also a venturi valve for good oxygenation. The water enters the filter via very large slots which does help prevent frequent blocking at the inlet. The fixing bracket has four large suckers although is quite bulky. The cable runs up the back of the filter very neatly.
For most of the Fluval U series, with the exception of the U1, there are three filter media baskets: Two sponge containing baskets with both filter sponge and a carbon pad with a third basket sandwiched in between supplied with ceramic biological media. This combination is effective and allows you to change or clean the filter media one at a time, preserving the bacteria colony. The plastic baskets make it really easy to keep the media nicely spaced out and easy to access, even if this does mean the filter itself is fairly large.
Good set of features, easy to maintain, quiet, good amount of filter media. The large inlet slots also allows it to go longer without blocking up.
The U1 only comes with a sponge and is very very bulky for the small amount of filter sponge it can hold.
One of the best internal filters and is solidly made.