mine has been skimming dry for the last 18 months. only recently when i switched from my 135 to my 54, my skimmer would only skim for about 2 days or so, and then the inside of the cone would become so covered in skimmate, that it would stop skimming. there would only be about 3/4" of skimmate in the collection cup. last night i decided to try skimming wet to see if that made any difference. over the weekend, i will be doing a mesh mod to my pump. hopefully that will make all the difference.