Hi Terry,
Maybe it's because I am a newbie, but I see no reason hyposalinity is better than copper, and I am curious as to why you do.
From what I have read in books and on this board, the problems with copper are that they kill inverts and corals, and is almost impossible to remove from liverock once it has been exposed for some time. It is removable from substrate with a good rinsing. The good associated with using copper is that it will kill parasites in a tank in a week with proper use.
The problems with hyposalinity are similar to those with copper in that hyposalinity will kill inverts and corals. But, in addition, it will kill all the good stuff on the liverock, effectively making liverock useless. Another problem with hyposalinity is that it takes a whole month for it to kill the parasites. And it makes sense to me that hyposalinity stresses the fish to the point that it weakens their immune system.
I must not know something because from what I have said, I cannot see why hyposalinity is better than copper. Can you tell me what I am missing?
sam