77a8cecc_Reefkeeping_Acronyms__STANDS_FOR
[ACRONYM] OTS [WHAT IT IS] Generally the result of gradual changes occurring in the water over a long period of time (many weeks to many months or even years ). Often recognized when old fish remain fine, but new fish die. [STANDS FOR] 
Old Tank Syndrome
Reefkeeping Acronyms
STANDS FOR