You must have seen that there are plenty of nanos'/picos out there without skimmers.
Taken from an article on nanoreef.com......
Now obviously any tank is gonna be better with a skimmer, but if the main website on nano reefs says they arent 100% essential, chances are it's probably true, or at least partially true.
Perhaps the skimmerless nano and pico tanks out there are using a type of vodoo sandbed magic, but who knows?
I get to be Layton for a day , and it's exciting!