Since it seems everyone else is fine, just curious on filtration - only carbon as a media? No filter pads or sponge/mechanical filtration?
Bump for actual parameter numbers (also, what kind of test kit?) and what activity/interaction you've had with the tank over the last month or so. (i've begun to keep logs and essentially a diary of interactions with the tank, it's helped me tremendously)
Unfortunately, the main thing sticking out to me is a Tang in a 60 gallon cube. My concerns are not enough swimming room, and the effect on their lateral lines. See here:
Lateral Line Erosion. I know a lot of "arbitrary" numbers exist on minimum tank sizes, and a lot of people claim that their larger fish is doing fine in a smaller tank... but my understanding (especially for tangs and fish with lateral lines) is they are under a constant stressor due to the glass walls. The more space the better, and "gallons" isn't the best measurement for spacial stress.