Good choice. I've been using fluval and no problems so far.currently running with a fluval 305. Didn't ocurred to me to search for fluval internal because i really never had one of them.Just external. Internal i had eheim.
Changed my mind because i read some bad reviews about the U1, i am getting a 400 l/h u2 but am turning the flow rate down so i get better filtration and dont upset the betta
either way, it goes from 45 to 110litres in your tank and i have 50 so the old one wouldnt cut it with 55