I had it for 1.5 years and recently upgraded to red sea 425. These are new coral frags which were doing quite good since few months but suddenly they started to turn white. I have done 40% water change this week and removed the parts which were turning white and treating the tank with Fauna Marin RTN/STN X for Tissue Nicrosis. I can see good results from last two days. I hope it continues but I still don't know what was wrong.