Rated 5 out of 5 by 1
Rated 5 out of 5 by mm2turfrog The U1 Fluval underwater filter is a highly
effective sponge filter.
Currently using in a 10G tank.
Unless i am mistaken, the description for this particular filter is misleading.
Yes, there is a flip top.
That's where the sponge goes.
There are no bio-balls or carbon inserts as those are used in the U2 and U3 underwater filter series.
It is adjustable like the other models.
U1 Fluval- is a Sponge only system
U2 " "-bio balls and 2carbon inserts
U3 -bio balls and 2carbon inserts
I personally like the simplicity and cost savings
of the U1
April 5, 2016