Today when I got home from school I found two of my Cory catfish dead. I had recently bought a uv sterilizer to combat the algae bloom in the tank. On Sunday I left it on for 3 hours then turned it off. On Monday I left it on for 2 hours then turned it off. When I got home the tank was clearing up significantly, but all my fish are dying or are going to die. My blood parrot cichild is laying on its side and it's breathing heavy. The only survivors where a rubber lip pleco my blood parrot cichild and one other Cory catfish. The water perimeters are fine I tested it last night and when I got home. I have no idea what too do.