Well purchased two yellow finned Damsels yesterday . This morning one missing . Well assume dead not to be found. Well tested water and amonia between 0 and 0.25 again. Well tested tap water with fresh kit = 0 tested water that was in rubbermaid and got same reading as water in tank. Tested water comming out of RO/DI = 0 So I know I'm makeing amonia in water and salt in container water is being stored in. Water with no salt added was stored since last saturday with power head in container . I mixed salt into water on this past wednesday and it's been in rubbermaid trash container since wednesday with the power head. Now the water was made last week with the RO/DI before I changed the filter cartriges. I'm totally frustrated with this tank. My daughter breaks every rule and has a healthy tank.