dawgdude;349243 wrote: well define need to add one. If you put a skimmer on your tank it would filter out dissolved organics in the water column. Your filters are mechanical and chemical that filter in a differnt way than a skimmer. You can't have water too clean however certain corals will grow better with dirty water. I would ditch the 50's and get a small airdriven skimmer. You thought you water was to clean but I know for a fact a skimmer will pull even more waste so I wouldn't worry about of ok your current set up. If you move to sps then you will need your water even cleaner than those filters will provide.