I have been using 100% R/O water and not treating it with anything for 18 months. I have not had anything die until the last 2 months and I have lost an angelfish, 2 neon tetras, 2 orange tetras and a cory. and all my assassin snails. I was in the chat room and someone said that using straight R/O water was a bad idea. Is he right? And what should I do about this die off I am having. It seems like they are getting a swimbladder infection. for days they swim like they are going against a current trying to reach the top of the tank. But only 1 fish gets it at a time. Its very weird. Please help!