For Salt mix I would use di water, as the watse filter will helps remove impurity from the water source . If you are using raw tape water , best is at least use a dechlorine solution to remove chlorine from the water which will kill bacteria in the tank . There is no right or wrong answer, every method has its pro and cons. If nsw is not available, I would just use tape water with Salt mix for tank cycling since the nitrate and phosphate level is going to rise anyway after cycling . After tank cycling is completed, then I would do a major water change with ro/ di water before adding live stocks. This would be a cheaper solution I feel. Sent from Singapore Reef Club mobile app