Reposting here for visibility on the coral specifically - would be a shame if anything happened to the scolly!!
Reef Tank oxygen depleted + inverts gone - next steps?
Due to an unfortunate accident cleaning my powerheads during a water change, I made my tank hypoxic (some strong citric acid in the water by toddler). The inverts basically perished within a minute (shrimp, snails, etc.) I noticed the problem when I came back up and the fish were upside down...
www.bareefers.org