I have an established tank 10 years plus. 150g, live rock, Refugium sump (trigger emerald 39), apex system with apex dc pump with flow of 688. Water chemistry is good (0 ammonia, 0 intrite, 5 nitrate, 0 phosphate, 8.1 PH). 2 reef breeder leds. Coral, anenome, 2” sand bed and 36 watt UV. Had 2 file fish, blue gas trigger, square back Anthius (1 male 2 female), Atlantic blue tang, tomini tang, 2 clown 3 green chromis, diamond back gobbi, a clam and 1 cleaner shrimp. One by one the fish are dying. As of today have 1 clown, 1 green chromis and the diamond gobbi. One of the female anthius had a big spot on the belly and was not eating. It died and removed it right away. We also purchased brown spotted rabbit in the past month which died with a few weeks. We have never used house hold cleaners near the tank at all. No air fresheners nothing goes near the tank. We mix our salt and have an aqidic life twist RODI system with 0 tds. I am totally frustrated and at a loss as to what is wrong. It is obvious that there some kind of bacteria in the water. Clam, corals and anemone appear to be doing fine as well as the sand sifter star fish. Does any one have any ideas and/or suggestions. Desperate