I have had sumpless tanks since 92 and just set up my first sump 4 mths ago. To get rid of surface scum you need lots of surface action, an aqua clear hang on filter works great and it can double as a fuge. I've never had a problem with bubbles in the water from too much surface agitation, it's always been the skimmer that put bubbles in the water
*Edit* if I didn't have my sump in the basement and had to put up with it under the stand, I wouldn't bother having one at all, it would be a bigger pain in the butt then its worth
