I had a sterile system... Went fallow and then QT everything using TTM for 3 years. After reading and some thoughtful research.. I started adding live black worms to my systems and feeding clams. The change in the color of my blue hippo tang was amazing! No ill effects on my fish at all. I am not as convinced as Paul B that it is the black worms OR the clams b/c I started enhancing their diet all at the same time. In retrospect I should have added one new improvement to observe the benefits.. BUT when you are making a change for the health of your fish.. I threw science aside and enhanced everything together. I also started supplementing with Selcon AND giving way more nori.
I am still QT my fish before they enter the DT... to teach them to eat worms, clams, mysis, and high quality flake. I also want to observe and ensure that they do not have velvet / ich so that if they do I have them in an environment where I can observe them better and treat them if needed.
Neptune
Good Luck.