There is more than 1 person here running a marine tank without a skimmer, i can think of 2 that i know straight away (me and steve-s) mind you, our tanks are only 30 Litres.... I think you mean, i know of 1 person here who runs a large marine tank (not nano or anything) who doesnt run a skimmer blah blah blah etc....
It can be done, but i, even though i dont have a skimmer, would advise having one....(my tank cant fit one) Also, dont use tap water for top up, i have no skimmer, and use tap water for top up ( :oops: at the moment anyways) and my tank is BROWN!!!! corals are looking good, but lots and lots of brown algae and cyano....