To skim or not to skim that is the question. I have head many conflicting reports on the use of skimmers while employing an ATS. I know the so called con's but think they may be over exaggerating the amount of "good stuff" they remove from the water. I have yet to read/see any scientific to back up the claim not to run a skimmer only some people who don't run skimmers with an ATS but many still do so. I turned my skimmer off for 2 weeks and apart from some red cyno appearing on my sand I noticed nothing else either good or bad. However when I turned my skimmer back on it pulled out a good about of foul smelling gunk. If anybody knows of any REAL scientific studies that have been published on ATS along with skimmers I would like to read them.