Heres what I know. I was told a story by a fellow fish junky a while back. I cant remember exactly where he was, but it was a tropical island of sorts, back in the 80s. He was there doing research on the local fish populations or osmething like that. Anyway, alot of people there had tanks but really had no idea of how to take care of them. Since freshwater was such a commidity our types of filteration and top off methods were not available. Poeple would literally just let things die, flush em and go out and catch more. While there he found out the plumbing for the septics and sewage was all saltwater. All the clean water coming into the toilets was simply being pumped in from the ocean, so, plumb a line from this supply to fish tank and drain line to drain pipe, and BAM!
So esentially yes, they were using ocean water to run their tanks.
So esentially yes, they were using ocean water to run their tanks.