This is true, you need to be careful not to have equipment or housing that generates electromagnetic charges (like electrolysis sp? found with concrete in salt water, or when metals come into contact with salt water).
Another problem, especially with youngsters is substrate - sugar fine sand is really best in most instances, though it's not so much a problem for adult sharks, but you still need to be careful.
Len, I'm sure you checked out the outdoor shark and ray areas of LBAOP, but I haven't been there for a while, is it still netted (they were having a problem with herons and other fishing birds taking the easy pickin's). I know that for the most part the aquarium has very good success with the sharks they choose. They're pretty careful what species they take on, as well, and I also know that they have sort of an exchange program with Monterey Bay aquarium. I have to admit, there are times when I really miss my work in the coral lab, mostly with the baby bamboo sharks.