Was told to use this in my tank instead of carbon or fluval brown filter stuff (can't remember the name) to help with ridding tank of cyano along with siphoning and water change. Well, since I have changed to this, my 2 clowns got white stuff on them and died, my new clown goby is dying and my tail spot Benny died. Not sure of coincidence or something else. Perimeters are great. Nitrate and nitrites low, ammonia low, salinity 1.024, temp 76-78f, 20% water change once a week. Inverts are doing well. Firefish has a couple spots but eating and moving about. Any thoughts? I am devastated losing my clowns.