Hi Randy, Honestly, those things I wrote here may not be true. I'm not confident about it at all. But because removing a skimmer is a bit scary thing to me, I wanted to hear people's opinions. Well, as some already pointed, the system is totally different for each tank, and it's not about which is better. But according to your comments, my assumption seems to be wrong! As brandon429 pointed, I want to know what's happening, too! But ammonia is not detected by now. I can't explain it!