Recently I slowely switched the water in my tank over to the R/O water from wal-mart. Shortly after doing so all life in my tank ceased to exist except for my corals. All fish and inverts died. I performed water tests and even had my lfs test the water and everything tested nearly perfect. About 3 months ago I slowly switched the tank to tap water and have no problems. All the corals are great and new fish are fine. Has anyone else had this problem and should I buy a RO unit or buy RO water from lfs?