I tried to introduce Wild Altums to my tank & had massive deaths. They must of been carrying a disease because they all died and my one healthy altum is on deaths row. The only fish left are 2 Plecos & 1 Bottom Feeder. Before I add new fish, how would you suggest cleaning the tank to ride any possible disease. I was going to do a very thorough gravel vacuum & clean all the filters while adding new media. I am running allot of bio media so this should keep my Biological system in check. Then I was going to do a 50% water change 2-3 times over the next week while keeping the tank at 86 deg. Would this eliminate all disease & how long would you weight before adding new fish.