i set up my tank a little over a month ago when my ammonia, nitrite, and nitrate read zero I put 4 yellowtail damsels all died one of which i have yet to find. my tank is a 55 gallon main tank with a 30 gallon refugium. Went and bought the last yellowtail my LFS had went to another and picked up three fourstriped damsels. One was doa the other two ate good replaced the one that died it died and another one died is there something else that could be causing death. oh yeah salinity is 1.023 ph 8.4