Not sure what brands are still around in Europe as I'm gone for 21 years now but Deltec I still around I think.
Reef Octopus is making great HOB skimmers
the BH 90 is one you can use on your 250L (60 gal)
I'd recommend deltec aswell , mines never missed a beat but as Watchmen said I'm not so sure they do a hang on
On my first tank that didn't have a sump I had a TMC hang on , it done the job but wasn't great .....sort of hard to get started once it gets turned off