I see over at the Seachem forum that you're adding some of their bottled bacteria at every water change. Did you have a cyano
issue before starting that?
If I remember right, in the beginning when your nitrates where through the roof, you were adding some type of "clean up" bacteria to your tank? You stopped adding the stuff - and did a bunch of other stuff too, granted - and your nitrate issues starting coming under control. My suggestion then was to just lay off the quick fix stuff and let your tank settle down. Maybe I missed something in this thread, but it seems like your tank was doing fine, but now all of a sudden you're adding/changing a fair amount of stuff all at once. (Think you just changed salt, too?) Just my 2 cents worth as usual, but I'd just slow down, take a deep breath, and let your tank mature on its own.