I have had aquariums all my life since i was a child. I currently have a 125g saltwater reef. 75g fresh water community tank. 29g breeder community tank. 6g fluval fresh water and a 60g hex fresh water, in which im getting ready to add Discus too. My question is.... does anyone know why i would have a oily film on the surface of my discus tank and if so what can i do about it. Thanks Concerned.