40 micron sprayers and inline filter?

I remember a true aeroponics thread on overgrow. I believe it said 40 micron sprayers were the optimun partical size, but I cant seem to find any quality ones or ones that even state partical sizes. Where do you guys get your goods?

Also, what do you guys use for a filter so the sprayers dont clog? I just switched to organics and my spayers are getting all screwed up. Just something simple that would be easy to clean. maybe something that could go inline on my 3/4 pvc.

Thanks my friends