i clean out my skimmer collection cup and wipe it down etc. every 3-4 days as well.
About the sock for the activated carbon, what I'm trying to describe is the fine mesh bag that people put carbon in..."filter sock" is probably not the right term. You can find them on most online vendors for aquarium supplies.
What is marine snow? I don't know about it, so I can't say whether the carbon will strip it out or not. Is it coral food?
About your nitrates....do you have a sump? If so, what's the bottom of it look like? Does it have a bunch of sediment/detritus on the bottom? If so, this may contributing to your elevated nitrates. You should in that case syphon or vaccum it out.
I also use 100 micron filter sock on my return pipe to the sump, and replace it with a clean one every 2-3 days. This keeps my sump a lot cleaner than it used to be.
As for your skimmer, the etss skimmer should work fine for you as long as you have the right kind of pressure pump for it and you replace your bioballs with new ones every 6 months. It's possible that the turning it on and off is keeping it from "dialing in" properly...I don't know. But you should be getting more skimmate than you are, so something isn't working right. The pump is a good place to start. Make sure it's a Mag drive, Iwaki, or other pressure rated pump.