My girlfriend just called me telling me she was doing a water change in her tank and would call me when she was done. Well I just heard from her and fish are probably dying. Her long nose hawkfish that is always out and about is nowhere to be found and her copper band butterfly is just basically looking like he is about to get sucked into the overflow. This same thing happened 2 weeks ago when doing a water change and 2 green chromis had died. Nothing was added or done to the tank. She uses a Kent Maxxima ro/di, lets the salt mix for a full day with a power head, and uses red sea coral pro salt. So far the fish arent dead, but she said theyre looking like they are on their way out. Hawkfish she has had for almost a year, butterly is about a week or so old. Any ideas what could be causing this? Anything to do for the fish now or are they pretty much dead in the water?