275L converts to 72 us gal
A nice size for a beginner .
You can get by with out a sump , I have for a few years in my 75 gal
I have a eheim canister with only filter floss .
Research the Berlin method .
Biological filtration and using 2lbs of live rock per gal
But you need a very good skimmer .
The problem with hang on back and canister filters they hold onto nitrates like a factory for nitrates .
Ideally you do not want any ( 0ppm ) or as close to as possible .
I would suggest do your research .
And understand everything well before jumping Into something of that degree .
What kind of skimmer are you talking about ?