i am losing my patients with salt water.after my nitrites went to 0.5 and i lost six fish i don't no what to do.my clowns were getting dark almost black and werent hanging out in there usual spot,there eyes were getting cloudy and one had a white piece of something hanging out of his mouth.i put a bag of charcoal in the filter and stuff for a new tank.its been cycling over two months and had bio filters that were in there over a year.i had a sea apple that killed all my fish wxcept two clowns and a goby.i cleaned the tank but do you think i should of bought new filters?i just tested water again and everything is perfect.nitrites of 0.5 is'nt enough to kill my fish is it.