<a href=showthread.php?s=&postid=12109771#post12109771 target=_blank>Originally posted</a> by capn_hylinur
It is not my point to judge here--only to be helpful--but your tank does not look healthy judging by the algae on the rock and the substrate and the positioning of your returns and korilia
The first question I would have would be flow issues--in the 90 gal you should have about 15x' tank turn over per hour.
That would be over 2000 gph. It doesn't look like you have that
Plus you need to have the surface churning for oxygen exchange and a good flow in and around the rock work and across the substrate. In order to accomplish that in your set up I would suggest three korilias and have one of the loc lines pushing straight down to the substrate.
The second question question is your filtration system. Do you have a sump and a protein skimmer?
BTW another way of giving tangs swimming area is to give them current---I have a turn over rate of 55 times in my tank and the tangs swimm against it all day, let the current push them back, swim against it again---kind of like hamsters in an exercise wheel:lol: