I clean mine when I change my filter sock about every 3 days.
I've got 80 gallons of water with 2 clownfish, a goby and a pygmy angel So maybe I'm a bit over cautious.
I do a 10 gallon water change every 2 weeks.
I love love love the skimmer I got from Wayne.
It's the easiest thing in the world to change and clean.
http://www.fishtanksdirect.com/Urchi...wMag5Pump.aspx
Overkill? just a teeeny bit.
that being said I'd rather clean my skimmer twice as often and forget about my filter sock! I HATE THOSE THINGS! EW!