I'm new to saltwater, I've had my tank set up for about 3 months. I started my tank with some purple rock and live sand. 2 weeks ago I added a white rock and some macro alge According to the fish store the rocks are already cured. Starting on Friday my butterfly fish died, Saturday my goby and my purple dottyback died. Sunday my clownfish died and today my angel died. I've put my remaining clownfish in a different tank and so far he's doing good. I have no idea what has killed my fish. After the first fish died I did a water change, my parameters are ph 8 not registered any nitrates or nitrites, no amonia, salinity 1.025 water temp 80. Please help I'm terrified to put my clown back in my tank and I don't know what to do. Do I throw out the rock and sand and start over? Drain the tank and sump?