Tangs with HLLE

[PFisher]

I need some advice. I currently have a Regal tang and a Sailfin tang that are showing signs of HLLE. I have read everything that I can find on the subject, which contains nothing conclusive. I found that the main causes seem to be nutrition, dinoflagelates, copper, carbon and high nitrates.

I recently had a large outbreak of dinoflagelates and it was shortly after this that the HLLE started to show up. By raising the pH to 8.5 and cutting light for a few days I was able to eradicate most of that nasty brown slime. But now I need to know how to help the tangs. I feed Nori daily along with PE Mysis and occasional Spirulina Brine. I have started using Vita Chem and Cyclop-Eze. Is there anything else that someone could recommend to ensure that this is not a nutrition problem? All of the other fish seem fine.

It is a long story, but during startup this tank also had some copper in the system for the first few months. But the copper is now gone, corals and snails are doing fine.

I have removed the carbon. Tank stats are as follows:
200 gallon with sump and refugium
pH = 8.5
Ca = 520ppm
KH = 10 dKH
NO3 = < 5ppm
SG = 1.025

Thanks for any help that you can offer.

Patrick