The aquarium started as a basic salt tank that only had fish but after college i tried to move it and lost everything, When i moved here I was broke so I started only a basic freshwater but still left the coral gravel in it I just rinsed it for hours and didnt have any problems for 8 yrs I lost power in a storm and lost all. the filter is just a whisper type and the heater is just a tube heater. I am thinking that the gravel should be disguarded but not sure. IM gonna have to buy lights