Hello everyone, i've had a 55 gallon fish only tank for about 4 years now, most of the fish are the age of the tank, the problem is my father asked me to set up a small 29 gallon tank for him with live rock and a few fish, after about 3 weeks he decided to take down, put his fish in my tank and the worst part he left all the live rock and live sand from his tank siiting in a bucket outside for 4 hours on a 20 degree day, the whole time i was at work, when i got home he had put the live rock and sand in my tank as well, after about 3 days all my fish are dying one at a time from what it looks to be velvet or really bad ich, i've try water changes, changed all media on both canister filters and even tried a lil sea cure copper, sorry for the long story but is there anything else i can do to try to help my remaining fish?? thank u all, Malcolm