[mike31154]

Well I guess I stand corrected. After a bit of research it does seem that some beneficials are removed by skimming, particularly by the more efficient skimmers available these days. However, depending on your system & what you keep, a certain amount of skimming is probably better than none at all. Having done the bit of research, I'm reassured that my counter current air stone driven model is a good choice for my system. I have no sump and have successfully kept a Mandarin in there for 5 years plus. I've never supplemented the tank with plankton or other additives & he doesn't appear to be starving! I must admit that he will take pellet food when it happens to come to rest on the substrate, which is not that often. Once in a while I try to target feed him with the pellets, but that's very rare occasion these days.