well if you no a coral is dead you have to get it out asap! thats probly it. open the hood to your tank or what ever and smell, does it stink?? if it does you need to make sure your skimmer is work , if you dont have one get one its the only way to pull junk out. far as the coral looking good , well ya they will open and look great but what it is doing there is starving for light so they open up as much as they can to ubsorb any nutrient from your lighting and from what you say about your light wattage--- well you no the problem then. not enogh light there going to die. run some chercoal for about 5 days that should clear it up. if you have a way with you filtration take a nylon and fil it with charcoal and rinse it out and put it in your filtration some were. you need to list in your info filtration your useing and such with lights and all. well be able to help you better.
life is to short blow all your money on yourself!
doing a planted freshwater tank
- 2 dogs
and a "ol" lady