I have 2 months old sw tank and I believe my tank has been gone through the cycle time. pH = 8 Nitrite = 0 Ammonia = 0 Nitrate = 5ppm Salinity 1.023 Temp 80F. I don't know why every time I add fishes in, they died next couple days. I am really frustrating now. I change 10% of water every week but fish died still died. What do I need to do? My husband gave me a nickname "fish killer". PLEASE HELP. I want to show my husband that I am not a FISH KILLER.