4 weeks ago I set up a 500 gallon tank. I swapped my cichlids from my 125 to the new tank.I used the sand and rock decor from the old tank plus new stuff. The first 3 weeks were fine. Water was clear and all was well.I came home this week to find my water cloudy and I am losing 1 fish per day.I have NEVER had any problems with my smaller tank so I am not sure how to fix this problem. I have to be honest.I have never needed to test water chemistry before,so I don't have the testing equipment.I intend to get the water tested today. If anyone has any thoughts/ideas I would appreciate the input.