I purchased the tank already, it was a good deal regardless of the fish, but she is including them. I am not able to pick up the tank for about 4 weeks because we are changing carpet before setting it up. So she still has it. I forgot to mention, she even has an anenome in it. I know it sounds bad, but it was a good deal. I just need to figure out how to get the conditions at least liveable, then I will work on making them good. I have a 55 and planned on moving her more aggressive fish like the tang to my 55 and moving some of mine over to hers and slowly reintroducing hers. But that was before I took a sample of water home and tested it. That's why I was wondering if a 75% water change would be possible without causing a crash. I need to get the trates down to a liveable condition before adding anything, especially the fish that I've carefully raised the past year. I would love to get the coral out immediately, but she is doing me a favor by keeping the tank until I get carpet, and I doubt she will be willing to do much to improve the conditions during this time. The other option I thought of, is taking all of her fish to a pet store for either store credit or if they won't do this, just give them to the store. Then I could set the tank up at my house, change out the cc to sand. Leave my tank as is, and after I get hers to acceptable levels make the change.
I really liked the tang and hoped on keeping it, but I think this might be the best alternative.
I forgot to add, she also has an anenome. She must have some tough corals and fish to still be alive.